Defined therapeutic microbiota and methods of use thereof

Abstract

Described herein are methods and compositions for the use of treating and/or preventing Clostridium difficile infections, including recurrent C. difficile infections, in a subject. Aspects of the technology relate to administering to a subject in need thereof a composition comprising a defined therapeutic microbiota comprising, e.g. Clostridial species. Also described herein are biomarker profiles, including a biomarker profile comprising two groups of Clostridial species, that is predictive of the likelihood of recurrent C. difficile infection and/or susceptibility to initial C. difficile infection.

Claims

1. A method of suppressing toxin production by C. difficile bacteria in a subject in need thereof, the method comprising orally administering a formulation comprising viable C. scindens and C. bifermentans bacteria in an amount effective to reduce C. difficile toxin by at least 10% as compared to the level of C. difficile toxin prior to treatment onset, wherein one or both of the C. scindens and C. bifermentans bacteria are in spore form or in dried viable form; and wherein the formulation comprises no other bacteria.

2. The method of claim 1, wherein the formulation comprises a capsule or microcapsule, or a composition comprising an enteric coating.

3. The method of claim 1, wherein the formulation further comprises a prebiotic.

4. The method of claim 1, wherein the subject has or has been diagnosed with, or is at risk of C. difficile infection.

5. The method of claim 4, wherein the C. difficile infection is recurrent.

6. The method of claim 1, wherein the formulation is administered before or concurrently with an antibiotic.

7. The method of claim 1, wherein the formulation is administered after a course of an antibiotic.

8. A method of suppressing toxin production by C. difficile bacteria in a subject in need thereof, the method comprising orally administering a formulation comprising viable C. scindens, C. bifermentans and Ruminococcus obeum bacteria in an amount effective to reduce C. difficile toxin by at least 10% as compared to the level of C. difficile toxin prior to treatment onset, wherein the C. scindens, C. bifermentans and R. obeum bacteria are in spore form or in dried viable form.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A-1J presents experimental data of C. difficile gnotobiotic mouse survival studies. FIG. 1A shows a schematic of the Gnotobiotic mouse colonization model of C. difficile infection. Adult Swiss-Webster mice were pre-colonized with a commensal species (C. bifermentans, C. scindens or C. sardiniense for 7 days, prior to oral challenge with 1000 C. difficile spores (ATCC 43255 strain). The survival curve shows the survival post-challenge with C. difficile. At least 8 mice across 2 experiments were assessed per timepoint. Biological samples for metabolomics and microbial gene expression analysis were taken at the following time points: GF controls (first arrow), after 7 days of commensal colonization (second arrow), at 20 hours of C. difficile infection (third arrow), alone or with the given pre-colonized commensal. At least 8 mice across 2 experiments were assessed per timepoint. FIG. 1B: Swiss-Webster germfree mice were associated with a commensal: C. bifermentans, C. sardiniense or C. scindens for 7 days, prior to challenge with 1000 spores of C. difficile strain ATCC43255. Control germfree mice received C. difficile alone. The survival curve shows the survival post-challenge with C. difficile. FIG. 1C. Body condition scores (BCS) of the mice were monitored daily to assess activity, feeding, grooming and tissue turgor for additional clinical symptoms of infection. Swiss-Webster germfree mice associated with a commensal: C. bifermetans, C. sardiniense, C. scindens, prior to challenge with 1000 spores of C. difficile strain ATCC43255. Control germfree mice received C. difficile alone. FIGS. 1D-1J show representative images of H&E stained sections of the colon of the mice. FIG. 1D shows a representative image of a healthy colon from a conventional mouse, 200× magnification showing intact epithelial crypts, mucosal and muscular layers. FIG. 1E shows a representative image of a colon of a Gnotobiotic mouse 24 hours after C. difficile infection showing denudation of the surface epithelium and massive neutrophil influx (200× magnification). FIG. 1F shows a representative image of colon of a Gnotobiotic mouse pre-colonized with C. sardiniense, 24 hr after C. difficile challenge showing massive tissue edema (arrow), epithelial denudation and neutrophil influx, consistent with a toxic megacolon picture (100× magnification). FIG. 1G shows a representative image of colon of a Gnotobiotic mouse pre-colonized with C. bifermentans, 24 hr after C. difficile challenge with some epithelial ballooning but no overt epithelial disruptions or tissue edema (200×). FIG. 1H shows a representative image of colon of a Gnotobiotic mouse with C. scindens 28 days after C. difficile challenge showing intact epithelium and residual inflammatory mucosal infiltrate consisting of neutrophils and lymphocytes (200×). FIG. 1I shows a representative image of colon of a Gnotobiotic mouse precolonized with C. scindens and 28 days after C. difficile challenge, showing a focal area of epithelial damage with surrounding intact epithelium and submucosal (200×). FIG. 1J shows a representative image of colon of a Gnotobiotic mouse precolonized with C. bifermentans at 28 days post-challenge with intact epithelium and submucosa. Resolving inflammatory infiltrates from infection, which are largely lymphocytic, can be seen. However, ongoing areas of focus epithelial damage were not noted.

(2) FIGS. 2A-2C present experimental data that shows that the commensal bacterium C. bifermentans suppresses toxin production by C. difficile. FIG. 2A shows the results of an ELISA of cecal contents from germfree Swiss-Webster mice that were collected at 24 and 48 hours after oral challenge with 1000 spores of the C. difficile ATCC-43255 strain. ToxinB was detected by ELISA and concentration in cecal contents calculated against a standard curve of purified toxinB. 4-8 mice were assayed per condition. Toxin levels in C. sardiniense pre-colonized mice were assessed from those that had survived to 24 or 48 hours. FIGS. 2B-2C present experimental data that show C. bifermentans suppresses toxin production without altering C. difficile biomass. FIG. 2B shows a bar graph showing C. difficile biomass in shed stool samples in the indicated days post-challenge. FIG. 2C shows the levels of C. difficile toxin production with indicated conditions. C. bifermentans precolonization prevents a spike in C. difficile toxin production.

(3) FIGS. 3A-3B show a schematic outlining of the infectious mouse model protocols using conventional mice and the therapeutic intervention. FIG. 3A shows a schematic of the therapeutic intervention: adult conventional mice were treated with intraperitoneal clindamycin 24 hours before receiving 1×10{circumflex over ( )}4 spores of C. difficile strain ATCC 43255. Approximately 20 hours after dosing, as mice first developed signs of symptomatic infection, animals received 5×10{circumflex over ( )}7 CFU of C. bifermentans or C. sardiniense, or control vehicle alone, by gavage and were monitored for 2 additional weeks. FIG. 3B shows the survival curves of clindamycin-treated conventional mice infected with C. difficile and gavaged 20 hours later, upon onset of symptomatic infection, with vehicle alone, 5×10{circumflex over ( )}7 CFU of C. bifermentans or 5×10.sup.7 CFU of C. sardiniense. At least 8 mice across 2 experimental replicates were studied for each condition.

(4) FIGS. 4A-4B present experimental data showing that Clostridium bifermentans is a highly proteolytic Stickland fermenting species. FIG. 4A shows representative images of chopped meat anaerobic culturing broth inoculated and incubated with either C. bifermentans, C. hiranonis, C. sardiniense, C. scindens, C. ramosum, or C. difficile and assessed for their proteolytic activity using a biochemical protease assay protease in a biological sample. FIG. 4B lists features of the strains with C. difficile, C. bifermentans, C. sardiniense and C. scindens.

(5) FIGS. 5A-5I present experimental data showing that Clostridium bifermentans promotes Stickland fermentation by the Gram-positive toxigenic bacterium C. difficile. The cecal contents of germfree Swiss-Webster mice were collected 20 hours after infection with C. difficile and untargeted metabolomic analysis of cecal samples was performed. FIGS. 5A-5D show the MassSpectometry profiles of Stickland acceptor amino acids in cecal contents of germfree Swiss-Webster mice at 20 hours of infection with C. difficile. Y axis is Log10 MassSpec units of detected compounds. X axis indicates experimental condition: GF-germfree controls (no bacteria); Cdiff-challenge with 1000 C. difficile spores of strain ATCC43255; CSAR-7 days mono-association with C. sardiniense; CBI-7 days mono-association with C. bifermentans; Cdiff+CSAR-mice mono-associated with C. sardiniense for 7 days followed by C. difficile challenge; Cdiff+CBI-mice mono-associated with C. bifermentans for 7 days followed by C. difficile challenge. Each group has 8 mice across two experimental replicates. FIG. 5E shows the Mass Spectrometry profiles of cecal branched-chain amino acids and degradation products in gnotobiotic colonized mice. MassSpectrometry profiles of Stickland donor, branched chain amino acids in cecal contents of germfree Swiss-Webster mice at 20 hours of infection with C. difficile. Y axis is Log10 MassSpec units of detected compounds. X axis indicates experimental condition: GF-germfree controls (no bacteria); Cdiff-challenge with 1000 C. difficile spores of strain ATCC43255; CSAR-7 days mono-association with C. sardiniense; CBI-7 days mono-association with C. bifermentans; Cdiff+CSAR-mice mono-associated with C. sardiniense for 7 days followed by C. difficile challenge; Cdiff+CBI-mice mono-associated with C. bifermentans for 7 days followed by C. difficile challenge. Each group has 8 mice across two experimental replicates. Leucine, isoleucine and valine; levels elevated in Cdiff+CSAR mice, consistent with toxic megacolon picture. Cdiff and CSAR+C. difficile infected mice, which have a more severe clinical and histologic picture have 10× elevated keto-acid derivatives of the BCAA over Cdiff+CBI colonized mice, providing potential biomarkers for a more severe infection. Hydroxy-acid intermediates showing elevation with CSAR alone and CSAR+Cdiff. Isolavaerate, branched-short chain fatty acid product of Stickland fermentations, present in cecal contents of mice colonized with C. difficile and/or C. bifermentans, indicating in vivo Stickland fermenting of leucine as a donor amino acids. Other branched SCFA, sobutyrate, isocaproate and Valerate were not assayable by this method and are not shown. FIG. 5F shows that C. difficile and C. bifermentans use aromatic amino acids in vivo in Stickland reactions. Cecal aromatic amino acids and metabolites in specifically-associated GF mice. Y-axis shows log 10 MS Units. X-axis indicates the colonized state of the mice. 8 adult Swiss-Webster mice at baseline (GF), +7 days commensal colonization with C. sardiniense (CSAR) or C. bifermentans (CBI), 20 hours of infection with C. difficile or 20 hours of infection after 7 days of commensal colonization (Cdiff CSAR, Cdiff+CBI). phenylalanine in cecal contents. Elevated amounts with Cdiff+CSAR relating to toxic megacolon picture. Stickland phenylalanine metabolites that are only present or elevated in mice associated with a Stickland fermenter. C. difficile is the dominant producer of phenylacetate, phenyllactate and phenylpyruvate. C. bifermentans is the dominant producer of phenylpropionate. Levels of C. diff dominant metabolites are reduced in the presence of C. bifermentans. Tryptophan levels and indoleacetate Stickland metabolite; other Stickland metabolites not present or detectable in the Metabolon panel. Both C. diff and CBI use tryptophan in Stickland reactions per elevated production of indoleacetate. tyrosine and Stickland tyrosine metabolites. Both species produce 4-hydroxphenylacetate. Cdiff specifically produces para-cresol (host sulfated derivative shown, native molecule not detected in Metabolon panel). CBI specifically produces 3(4-hydroyphenyl-propionate). FIG. 5G shows the commensal and C. difficile carbohydrate utilization in vivo. Cecal sugars and metabolites in specifically-associated GF mice. Y-axis shows log 10 MS Units. X-axis indicates the colonized state of the mice. 8 adult Swiss-Webster mice at baseline (GF), +7 days commensal colonization with C. sardiniense (CSAR) or C. bifermentans (CBI), 20 hours of infection with C. difficile (C. difficile) or 20 hours of infection after 7 days of commensal colonization (Cdiff CSAR, Cdiff+CBI). Baseline levels of sugars and metabolites shown in germfree mice. When metabolized microbially, amounts decrease from baseline. Levels of glucose in germfree mice versus those colonized with single species show some glucose use by commensals or C. difficile but levels increase when two species are co-colonized. Commensal and C. difficile metabolize fructose in cecal contents with inhibition of metabolism when co-colonized. C. difficile alone metabolizes mannitol/sorbitol with some inhibition of metabolism when co-colonized with C. saridniense. Elevated pyruvate produced in infections with C. difficile or C. difficile+CSAR. Lactate levels increase with C. difficile infection by itself or with commensals. Succinate levels increase with C. difficile by itself or with CSAR but do not change significantly with CBI as compared to CBI-alone. FIG. 5H-5I shows a representative Mass Spectrometry plot for C. sardiniense (CSAR) (FIG. 5H) and for C. bifermentans (CBI) (FIG. 5I).

(6) FIGS. 6A-6B presents the experimental results of C. difficile Short Chain Fatty Acids (SCFA) profile produced in vitro. FIG. 6A shows the concentrations of C. difficile Short Chain Fatty Acids (SCFA) produced in vitro (mM). Cultures were grown in 10 mL of pre-reduced peptone-yeast (PY) broth at starting pH=7 with 1% glucose, 1% mannitol or 1% sorbitol for 72 hours at 37° C. under anaerobic conditions. 100 uL of broth supernatant was extracted and run on an Agilent GC/LC flame ionization detector (FID) instrument with internal standard to quantitate production of short chain fatty acids acetate, propionate and butyrate and the branched short chain fatty acids isobutyrate, isovalerate, isocaproate, valerate or capropate. ND=Not detected below the threshold of detection. FIG. 6B shows the experimental results of the commensal Short Chain Fatty Acids (SCFA) profiles produced in vitro (mM). Millimolar concentrations of SCFA in liquid culture supernatants. Cultures were grown in 10 mL of pre-reduced peptone-yeast (PY) broth or PY+1% glucose (PYG), for 24 hours at 37° C. under anaerobic conditions. 100 uL of broth supernatant was extracted and run on an Agilent GCLC flame ionization detector (FID) instrument with internal standard to quantitate production of short chain fatty acids acetate, propionate and butyrate and the branched short chain fatty acids isobutyrate, isovalerate and isocaproate. ND=Not detected below the threshold of detection; caproate and valerate were not detected in the commensals (data not shown).

(7) FIG. 7 presents the experimental results showing the gene expression of the C. difficile toxin PaLoc and eut (ethanolamine) operon. Comparison of PaLoc and eut gene expression by bacterial RNAseq of cecal contents from C. difficile-infected gnotobiotic Swiss-Webster mice at 20 hours post-inoculation, compared with C. bifermentans colonized mice for 7 days prior to challenge with C. difficile for 20 hours. At least 4 mice/group evaluated. C. bifermentans colonized mice show a >48× decrease in C. difficile tcdR gene expression with concomitant >10× decreases in toxinA (tcdA) and toxinB (tcdB) gene expression. In contrast, C. difficile structural proteins for the ethanolamine carboxysome (eutH, eutK, eutL, eutN) are up-regulated >10× when C. difficile is inoculated into a C. bifermentans-colonized mouse.

(8) FIGS. 8A-8B show a schematic of Stickland Donor Branched Chain Amino Acids (FIG. 8A) and Stickland Donor Aromatic Amino Acids (FIG. 8B).

(9) FIG. 9 shows a schematic of the metabolic pathways utilized by C. difficile.

DETAILED DESCRIPTION

(10) By its very name, C. difficile is notorious for being difficult to treat. Not only is the C. difficile organism resistant to multiple antibiotics commonly used to treat bacterial infections in clinical settings (e.g., aminoglycosides, lincomycin, tetracyclines, erythromycin, clindamycin, penicillins, cephalosporins, and fluoroquinolones), but the use of such antibiotics to treat other infections is one of the greatest risk factors for developing C. difficile pathology. Add to that the ability of C. difficile to sporulate and essentially wait until even an antibiotic that kills its metabolically active form is gone, and it truly deserves its name and reputation.

(11) Toxigenic strains of C. difficile cause pseudomembranous colitis, a severe infectious disease of the colon. Infection often arises with disruptions to the gut microbiota, commonly after use of antibiotics that ablate protective commensals. C. difficile elaborates toxins when starved for carbon, nitrogen or energy (=high levels of NAD+). The toxins rapidly destroy the gut epithelial barrier enabling release of host-derived proteins and carbohydrate sources into the gut lumen which the pathogen then metabolizes. When co-existing with “beneficial” commensal species, C. difficile remains energetically stable and does not elaborate significant toxin. For patients failing multiple rounds of antibiotic treatment, who develop recurrent C. difficile infections, fecal microbiota transplant (FMT) is highly efficacious through its restoration of healthy gut microbial communities. However, the mechanisms of action of FMT, and specific microbes needed to halt toxin production and reduce pathogen biomass remain ill-defined. While microbial conversion of primary host bile acids to secondary acids have been hypothesized to play a key role, mechanisms of action have highlighted effects upon germination of C. difficile spores (primary bile acids stimulate; secondary bile acids inhibit) and less so on metabolic factors that modulate toxin production or overall pathogen biomass.

(12) The technology described herein is related to the discovery of commensal bacteria that can suppress toxin production by Gram-positive toxigenic bacteria such as C. difficile and thereby treat or prevent the development of toxin-mediated pathology. Indeed, it was found that as few as a single species of bacteria can provide complete protection from otherwise fatal C. difficile infection in murine models described herein. Suppression of toxin production provides an alternative route to treatment of C. difficile-mediated pathology, in that it can be sufficient for treatment to just suppress production of the pathology-generating toxin without necessarily killing the microbe.

(13) It is discovered that commensal bacteria that suppress toxin production by Gram-positive toxigenic bacteria such as C. difficile strongly express and secrete protease enzyme activity that generates free amino acids that can be fermented by C. difficile via Stickland fermentation, which metabolizes free amino acids to generate energy. Without wishing to be bound by theory, the picture that emerges is that in order to avoid toxin production by Gram-positive toxigenic bacteria such as C. difficile, the gut environment needs to provide energy and nutrients sufficient to keep such bacteria from becoming stressed and responding by toxin production. Thus, commensal bacteria that secrete proteolytic enzymes can provide therapeutic benefits in suppressing toxin production by Stickland-fermenting Gram-positive toxigenic bacteria such as C. difficile. It is noted that among the protective commensal species found to have protective effects were bacteria that are themselves capable of Stickland fermentation, including, for example, C. bifermentans and C. scindens.

(14) Examination of the effects of protective commensals as described herein provides insights into the mechanisms of protection and further targets for manipulation of toxin production and biomarkers useful for evaluation of, for example, the likelihood of C. difficile recurrence, or the efficacy of treatment.

(15) The following provides additional details regarding C. difficile and the discoveries of highly protective/therapeutic commensal species, and considerations to facilitate the performance of the methods and compositions for the prevention, treatment, prognosis and diagnosis that exploit these discoveries.

(16) Clostridium difficile

(17) Clostridium is a genus of Gram-positive bacteria including around 100 species, which includes several significant human pathogens, including the causative agent of botulism and an important cause of diarrhea, Clostridium difficile. Pathogenic Clostridium strains include but are not limited to C. botulinum that can produce botulinum toxin in food or wounds and can cause botulism. Clostridium difficile can flourish when other members of the gut microbiota are killed during antibiotic therapy, leading to superinfection and potentially fatal pseudomembranous colitis (a severe necrotizing disease of the large intestine). Clostridium perfringens causes a wide range of symptoms, from food poisoning to cellulitis, fasciitis, and gas gangrene. Clostridium tetanii causes tetanus. Clostridium sordellii can cause a fatal infection in rare cases after medical abortions.

(18) C. difficile is a Gram-positive, anaerobic, spore-forming and toxin-producing bacillus, belonging to cluster XI of the Clostridium genus and commonly occurs in the hospital environment, and in the intestines of humans and domesticated animals. C. difficile can cause a spectrum of clinical conditions in humans, collectively known as C. difficile infections (CDI), which range from mild and possibly recurrent diarrhea to life-threatening complications such as pseudomembranous colitis (PMC), toxic megacolon and colonic perforation. As discussed elsewhere herein, C. difficile can occur in the gut of healthy individuals, but be maintained at a level that does not cause illness and/or have the expression of C. difficile toxin suppressed to a degree that the organism does not cause illness.

(19) The clinical spectrum of C. difficile ranges from asymptomatic colonization, mild and self-limiting disease to a severe, life-threatening pseudomembranous colitis, toxic megacolon, sepsis and death. CDI is defined when there is the presence of symptomatic diarrhea defined by three or more unformed stools per 24 h and at least one of the following criteria: a positive laboratory assay for C. difficile toxin A and/or B or toxin-producing C. difficile organism in a stool sample or pseudomembranous colitis or colonic histopathology characteristic of CDI revealed by endoscopy. Toxin is detected, e.g., by immunoassay for the A and or B toxin proteins, and/or by RT-PCR for the toxin-encoding nucleic acids. CDI can be associated with an increased abundance of toxin-producing C. difficile strains, leading to high toxin concentrations within the colon resulting in inflammation and damage of the colonocytes.

(20) The various strains of C. difficile may be classified by a number of methods. One of the most commonly used is polymerase chain reaction (PCR) ribotyping in which PCR is used to amplify the 16S-23S rRNA gene intergenic spacer region of C. difficile. Reaction products from this provide characteristic band patterns identifying the bacterial ribotype of isolates. Toxinotyping is another typing method in which the restriction patterns derived from DNA coding for the C. difficile toxins are used to identify strain toxinotype. The differences in restriction patterns observed between toxin genes of different strains are also indicative of sequence variation within the C. difficile toxin family. Toxin B shows sequence variation in some regions. For example, there's an approximate 13% sequence difference with the C-terminal 60 kDa region of toxinotype 0 Toxin B compared to the same region in toxinotype III.

(21) C. difficile uses a variety of carbon and nitrogen sources for energy and metabolism. Within the gut environment, these sources can originate from the diet, from other commensals, or from the host, particularly when elaborating toxin to disrupt mucosal barriers. Known carbon sources include sugars such as glucose, fructose, mannose, mannitol or sorbitol, the latter two of which are poorly absorbed in the gut and reach the colon. Sources of carbon and nitrogen include amino groups and ethanolamine, a breakdown product of host phosphatidyl ethanolamine from eukaryotic cell membranes, other commensals, or the diet. As noted elsewhere herein, when preferred energy sources or nutrients for C. difficile run low or become limiting, C. difficile toxin production is induced.

(22) C. difficile Toxins

(23) As noted above, C. difficile encodes two toxin proteins, referred to as TcdA and TcdB, or simply herein as C. difficile toxin A and toxin B. TcdA and TcdB are broadly classified as AB toxins, wherein a B subunit is involved in the delivery of an enzymatic A subunit into the cytosol of a target cell. The enzymatic A subunit of TcdA is an N-terminal glucosyltransferase domain (GTD) that inactivates members of the Rho family of small GTPases by glucosylation. The B subunit is composed of three regions: a combined repetitive oligopeptides (CROPS) domain, a delivery/pore-forming domain and an autoprocessing domain (APD).

(24) TcdA is encoded by the tcdA gene. Sequences for TcdA are known for a number of species, e.g., for C. difficile 630 (the TcdA NCBI Gene ID is 4914076) and polypeptide sequence (e.g., YP_001087137.1 (SEQ ID NO: 1). The sequence for the TcdA polypeptide is as follows (SEQ ID NO: 1):

(25) TABLE-US-00001 (SEQ ID No: 1)    1 msliskeeli klaysirpre neyktiltnl deynklttnn nenkylqlkk lnesidvfmn   61 kyktssrnra lsnlkkdilk eviliknsnt spveknlhfv wiggevsdia leyikqwadi  121 naeyniklwy dseaflvntl kkaivesstt ealqlleeei qnpqfdnmkf ykkrmefiyd  181 rqkrfinyyk sqinkptvpt iddiikshlv seynrdetvl esyrtnslrk insnhgidir  241 anslfteqel lniysqelln rgnlaaasdi vrllalknfg gvyldvdmlp gihsdlfkti  301 srpssigldr wemikleaim kykkyinnyt senfdkldqq lkdnfkliie sksekseifs  361 klenlnvsdl eikiafalgs vinqaliskq gsyltnlvie qvknryqfln qhlnpaiesd  421 nnftdttkif hdslfnsata ensmfltkia pylqvgfmpe arstislsgp gayasayydf  481 inlqentiek tlkasdlief kfpennlsql teqeinslws fdqasakyqf ekyvrdytgg  541 slsedngvdf nkntaldkny llnnkipsnn veeagsknyv hyiiqlqgdd isyeatcnlf  601 sknpknsiii qrnmnesaks yflsddgesi lelnkyripe rlknkekvkv tfighgkdef  661 ntsefarlsv dslsneissf ldtikldisp knvevnllgc nmfsydfnve etypgkllls  721 imdkitstlp dvnknsitig anqyevrins egrkellahs gkwinkeeai msdlsskeyi  781 ffdsidnklk aksknipgla sisediktll ldasvspdtk filnnlklni essigdyiyy  841 eklepvknii hnsiddlide fnllenvsde lyelkklnnl dekylisfed isknnstysv  901 rfinksnges vyvetekeif skysehitke istiknsiit dvngnlldni qldhtsqvnt  961 lnaaffiqsl idyssnkdvl ndlstsvkvq lyaqlfstgl ntiydsiqlv nlisnavndt 1021 invlptiteg ipivstildg inlgaaikel ldehdpllkk eleakvgvla inmslsiaat 1081 vasivgigae vtifllpiag isagipslvn nelilhdkat svvnyfnhls eskkygplkt 1141 eddkilvpid dlviseidfn nnsiklgtcn ilameggsgh tvtgnidhff sspsisship 1201 slsiysaigi etenldfskk immlpnapsr vfwwetgavp glrslendgt rlldsirdly 1261 pgkfywrfya ffdyaittlk pvyedtniki kldkdtrnfi mptittneir nklsysfdga 1321 ggtyslllss ypistninls kddlwifnid nevreisien gtikkgklik dvlskidink 1381 nkliignqti dfsgdidnkd ryifltceld dkisliiein lvaksyslll sgdknylisn 1441 lsniiekint lgldskniay nytdesnnky fgaisktsqk siihykkdsk nilefyndst 1501 lefnskdfia edinvfmkdd intitgkyyv dnntdksidf sislvsknqv kvnglylnes 1561 vyssyldfvk nsdghhntsn fmnlfldnis fwklfgfeni nfvidkyftl vgktnlgyve 1621 ficdnnknid iyfgewktss skstifsgng rnvvvepiyn pdtgedists ldfsyeplyg 1681 idryinkvli apdlytslin intnyysney ypeiivlnpn tfhkkvninl dsssfeykws 1741 tegsdfilvr yleesnkkil qkirikgils ntqsfnkmsi dfkdikklsl gyimsnfksf 1801 nseneldrdh lgfkiidnkt yyydedsklv kglininnsl fyfdpiefnl vtgwqtingk 1861 kyyfdintga alisykiing khfyfnndgv mqlgvfkgpd gfeyfapant qnnniegqai 1921 vyqskfltln gkkyyfdnds kavtgwriin nekyyfnpnn aiaavglqvi dnnkyyfnpd 1981 taiiskgwqt vngsryyfdt dtaiafngyk tidgkhfyfd sdcvvkigvf stsngfeyfa 2041 pantynnnie gqaivyqskf ltlngkkyyf dnnskavtgw qtidskkyyf ntntaeaatg 2101 wqtidgkkyy fntntaeaat gwqtidgkky yfntntaias tgytiingkh fyfntdgimq 2161 igvfkgpngf eyfapantda nniegqaily gnefltlngk kyyfgsdska vtgwriinnk 2221 kyyfnpnnai aaihlctinn dkyyfsydgi lqngyitier nnfyfdanne skmvtgvfkg 2281 pngfeyfapa nthnnniegq aivyqnkflt lngkkyyfdn dskavtgwqt idgkkyyfnl 2341 ntaeaatgwq tidgkkyyfn lntaeaatgw qtidgkkyyf ntntfiastg ytsingkhfy 2401 fntdgimqig vfkgpngfey fapanthnnn iegqailyqn kfltlngkky yfgsdskavt 2461 glrtidgkky yfntntavav tgwqtingkk yyfntntsia stgytiisgk hfyfntdgim 2521 qigvfkgpdg feyfapantd anniegqair yqnrflylhd niyyfgnnsk aatgwvtidg 2581 nryyfepnta mgangyktid nknfyfrngl pqigvfkgsn gfeyfapant danniegqai 2641 ryqnrflhll gkiyyfgnns kavtgwqtin gkvyyfmpdt amaaagglfe idgviyffgv 2701 dgvkapgiyg

(26) The tcdA gene sequence for C. difficile 630 is as follows (SEQ ID NO:2):

(27) TABLE-US-00002 (SEQ ID NO: 2)    1 atgtctttaa tatctaaaga agagttaata aaactcgcat atagcattag accaagagaa   61 aatgagtata aaactatact aactaattta gacgaatata ataagttaac tacaaacaat  121 aatgaaaata aatatttaca attaaaaaaa ctaaatgaat caattgatgt ttttatgaat  181 aaatataaaa cttcaagcag aaatagagca ctctctaatc taaaaaaaga tatattaaaa  241 gaagtaattc ttattaaaaa ttccaataca agccctgtag aaaaaaattt acattttgta  301 tggataggtg gagaagtcag tgatattgct cttgaataca taaaacaatg ggctgatatt  361 aatgcagaat ataatattaa actgtggtat gatagtgaag cattcttagt aaatacacta  421 aaaaaggcta tagttgaatc ttctaccact gaagcattac agctactaga ggaagagatt  481 caaaatcctc aatttgataa tatgaaattt tacaaaaaaa ggatggaatt tatatatgat  541 agacaaaaaa ggtttataaa ttattataaa tctcaaatca ataaacctac agtacctaca  601 atagatgata ttataaagtc tcatctagta tctgaatata atagagatga aactgtatta  661 gaatcatata gaacaaattc tttgagaaaa ataaatagta atcatgggat agatatcagg  721 gctaatagtt tgtttacaga acaagagtta ttaaatattt atagtcagga gttgttaaat  781 cgtggaaatt tagctgcagc atctgacata gtaagattat tagccctaaa aaattttggc  841 ggagtatatt tagatgttga tatgcttcca ggtattcact ctgatttatt taaaacaata  901 tctagaccta gctctattgg actagaccgt tgggaaatga taaaattaga ggctattatg  961 aagtataaaa aatatataaa taattataca tcagaaaact ttgataaact tgatcaacaa 1021 ttaaaagata attttaaact cattatagaa agtaaaagtg aaaaatctga gatattttct 1081 aaattagaaa atttaaatgt atctgatctt gaaattaaaa tagctttcgc tttaggcagt 1141 gttataaatc aagccttgat atcaaaacaa ggttcatatc ttactaacct agtaatagaa 1201 caagtaaaaa atagatatca atttttaaac caacacctta acccagccat agagtctgat 1261 aataacttca cagatactac taaaattttt catgattcat tatttaattc agctaccgca 1321 gaaaactcta tgtttttaac aaaaatagca ccatacttac aagtaggttt tatgccagaa 1381 gctcgctcca caataagttt aagtggtcca ggagcttatg cgtcagctta ctatgatttc 1441 ataaatttac aagaaaatac tatagaaaaa actttaaaag catcagattt aatagaattt 1501 aaattcccag aaaataatct atctcaattg acagaacaag aaataaatag tctatggagc 1561 tttgatcaag caagtgcaaa atatcaattt gagaaatatg taagagatta tactggtgga 1621 tctctttctg aagacaatgg ggtagacttt aataaaaata ctgccctcga caaaaactat 1681 ttattaaata ataaaattcc atcaaacaat gtagaagaag ctggaagtaa aaattatgtt 1741 cattatatca tacagttaca aggagatgat ataagttatg aagcaacatg caatttattt 1801 tctaaaaatc ctaaaaatag tattattata caacgaaata tgaatgaaag tgcaaaaagc 1861 tactttttaa gtgatgatgg agaatctatt ttagaattaa ataaatatag gatacctgaa 1921 agattaaaaa ataaggaaaa agtaaaagta acctttattg gacatggtaa agatgaattc 1981 aacacaagcg aatttgctag attaagtgta gattcacttt ccaatgagat aagttcattt 2041 ttagatacca taaaattaga tatatcacct aaaaatgtag aagtaaactt acttggatgt 2101 aatatgttta gttatgattt taatgttgaa gaaacttatc ctgggaagtt gctattaagt 2161 attatggaca aaattacttc cactttacct gatgtaaata aaaattctat tactatagga 2221 gcaaatcaat atgaagtaag aattaatagt gagggaagaa aagaacttct ggctcactca 2281 ggtaaatgga taaataaaga agaagctatt atgagcgatt tatctagtaa agaatacatt 2341 ttttttgatt ctatagataa taagctaaaa gcaaagtcca agaatattcc aggattagca 2401 tcaatatcag aagatataaa aacattatta cttgatgcaa gtgttagtcc tgatacaaaa 2461 tttattttaa ataatcttaa gcttaatatt gaatcttcta ttggtgatta catttattat 2521 gaaaaattag agcctgttaa aaatataatt cacaattcta tagatgattt aatagatgag 2581 ttcaatctac ttgaaaatgt atctgatgaa ttatatgaat taaaaaaatt aaataatcta 2641 gatgagaagt atttaatatc ttttgaagat atctcaaaaa ataattcaac ttactctgta 2701 agatttatta acaaaagtaa tggtgagtca gtttatgtag aaacagaaaa agaaattttt 2761 tcaaaatata gcgaacatat tacaaaagaa ataagtacta taaagaatag tataattaca 2821 gatgttaatg gtaatttatt ggataatata cagttagatc atacttctca agttaataca 2881 ttaaacgcag cattctttat tcaatcatta atagattata gtagcaataa agatgtactg 2941 aatgatttaa gtacctcagt taaggttcaa ctttatgctc aactatttag tacaggttta 3001 aatactatat atgactctat ccaattagta aatttaatat caaatgcagt aaatgatact 3061 ataaatgtac tacctacaat aacagagggg atacctattg tatctactat attagacgga 3121 ataaacttag gtgcagcaat taaggaatta ctagacgaac atgacccatt actaaaaaaa 3181 gaattagaag ctaaggtggg tgttttagca ataaatatgt cattatctat agctgcaact 3241 gtagcttcaa ttgttggaat aggtgctgaa gttactattt tcttattacc tatagctggt 3301 atatctgcag gaataccttc attagttaat aatgaattaa tattgcatga taaggcaact 3361 tcagtggtaa actattttaa tcatttgtct gaatctaaaa aatatggccc tcttaaaaca 3421 gaagatgata aaattttagt tcctattgat gatttagtaa tatcagaaat agattttaat 3481 aataattcga taaaactagg aacatgtaat atattagcaa tggagggggg atcaggacac 3541 acagtgactg gtaatataga tcactttttc tcatctccat ctataagttc tcatattcct 3601 tcattatcaa tttattctgc aataggtata gaaacagaaa atctagattt ttcaaaaaaa 3661 ataatgatgt tacctaatgc tccttcaaga gtgttttggt gggaaactgg agcagttcca 3721 ggtttaagat cattggaaaa tgacggaact agattacttg attcaataag agatttatac 3781 ccaggtaaat tttactggag attctatgct tttttcgatt atgcaataac tacattaaaa 3841 ccagtttatg aagacactaa tattaaaatt aaactagata aagatactag aaacttcata 3901 atgccaacta taactactaa cgaaattaga aacaaattat cttattcatt tgatggagca 3961 ggaggaactt actctttatt attatcttca tatccaatat caacgaatat aaatttatct 4021 aaagatgatt tatggatatt taatattgat aatgaagtaa gagaaatatc tatagaaaat 4081 ggtactatta aaaaaggaaa gttaataaaa gatgttttaa gtaaaattga tataaataaa 4141 aataaactta ttataggcaa tcaaacaata gatttttcag gcgatataga taataaagat 4201 agatatatat tcttgacttg tgagttagat gataaaatta gtttaataat agaaataaat 4261 cttgttgcaa aatcttatag tttgttattg tctggggata aaaattattt gatatccaat 4321 ttatctaata ttattgagaa aatcaatact ttaggcctag atagtaaaaa tatagcgtac 4381 aattacactg atgaatctaa taataaatat tttggagcta tatctaaaac aagtcaaaaa 4441 agcataatac attataaaaa agacagtaaa aatatattag aattttataa tgacagtaca 4501 ttagaattta acagtaaaga ttttattgct gaagatataa atgtatttat gaaagatgat 4561 attaatacta taacaggaaa atactatgtt gataataata ctgataaaag tatagatttc 4621 tctatttctt tagttagtaa aaatcaagta aaagtaaatg gattatattt aaatgaatcc 4681 gtatactcat cttaccttga ttttgtgaaa aattcagatg gacaccataa tacttctaat 4741 tttatgaatt tatttttgga caatataagt ttctggaaat tgtttgggtt tgaaaatata 4801 aattttgtaa tcgataaata ctttaccctt gttggtaaaa ctaatcttgg atatgtagaa 4861 tttatttgtg acaataataa aaatatagat atatattttg gtgaatggaa aacatcgtca 4921 tctaaaagca ctatatttag cggaaatggt agaaatgttg tagtagagcc tatatataat 4981 cctgatacgg gtgaagatat atctacttca ctagattttt cctatgaacc tctctatgga 5041 atagatagat atatcaataa agtattgata gcacctgatt tatatacaag tttaataaat 5101 attaatacca attattattc aaatgagtac taccctgaga ttatagttct taacccaaat 5161 acattccaca aaaaagtaaa tataaattta gatagttctt cttttgagta taaatggtct 5221 acagaaggaa gtgactttat tttagttaga tacttagaag aaagtaataa aaaaatatta 5281 caaaaaataa gaatcaaagg tatcttatct aatactcaat catttaataa aatgagtata 5341 gattttaaag atattaaaaa actatcatta ggatatataa tgagtaattt taaatcattt 5401 aattctgaaa atgaattaga tagagatcat ttaggattta aaataataga taataaaact 5461 tattactatg atgaagatag taaattagtt aaaggattaa tcaatataaa taattcatta 5521 ttctattttg atcctataga atttaactta gtaactggat ggcaaactat caatggtaaa 5581 aaatattatt ttgatataaa tactggagca gctttaatta gttataaaat tattaatggt 5641 aaacactttt attttaataa tgatggtgtg atgcagttgg gagtatttaa aggacctgat 5701 ggatttgaat attttgcacc tgccaatact caaaataata acatagaagg tcaggctata 5761 gtttatcaaa gtaaattctt aactttgaat ggcaaaaaat attattttga taatgactca 5821 aaagcagtca ctggatggag aattattaac aatgagaaat attactttaa tcctaataat 5881 gctattgctg cagtcggatt gcaagtaatt gacaataata agtattattt caatcctgac 5941 actgctatca tctcaaaagg ttggcagact gttaatggta gtagatacta ctttgatact 6001 gataccgcta ttgcctttaa tggttataaa actattgatg gtaaacactt ttattttgat 6061 agtgattgtg tagtgaaaat aggtgtgttt agtacctcta atggatttga atattttgca 6121 cctgctaata cttataataa taacatagaa ggtcaggcta tagtttatca aagtaaattc 6181 ttaactttga atggtaaaaa atattacttt gataataact caaaagcagt taccggatgg 6241 caaactattg atagtaaaaa atattacttt aatactaaca ctgctgaagc agctactgga 6301 tggcaaacta ttgatggtaa aaaatattac tttaatacta acactgctga agcagctact 6361 ggatggcaaa ctattgatgg taaaaaatat tactttaata ctaacactgc tatagcttca 6421 actggttata caattattaa tggtaaacat ttttatttta atactgatgg tattatgcag 6481 ataggagtgt ttaaaggacc taatggattt gaatattttg cacctgctaa tacggatgct 6541 aacaacatag aaggtcaagc tatactttac caaaatgaat tcttaacttt gaatggtaaa 6601 aaatattact ttggtagtga ctcaaaagca gttactggat ggagaattat taacaataag 6661 aaatattact ttaatcctaa taatgctatt gctgcaattc atctatgcac tataaataat 6721 gacaagtatt actttagtta tgatggaatt cttcaaaatg gatatattac tattgaaaga 6781 aataatttct attttgatgc taataatgaa tctaaaatgg taacaggagt atttaaagga 6841 cctaatggat ttgagtattt tgcacctgct aatactcaca ataataacat agaaggtcag 6901 gctatagttt accagaacaa attcttaact ttgaatggca aaaaatatta ttttgataat 6961 gactcaaaag cagttactgg atggcaaacc attgatggta aaaaatatta ctttaatctt 7021 aacactgctg aagcagctac tggatggcaa actattgatg gtaaaaaata ttactttaat 7081 cttaacactg ctgaagcagc tactggatgg caaactattg atggtaaaaa atattacttt 7141 aatactaaca ctttcatagc ctcaactggt tatacaagta ttaatggtaa acatttttat 7201 tttaatactg atggtattat gcagatagga gtgtttaaag gacctaatgg atttgaatac 7261 tttgcacctg ctaatactca taataataac atagaaggtc aagctatact ttaccaaaat 7321 aaattcttaa ctttgaatgg taaaaaatat tactttggta gtgactcaaa agcagttacc 7381 ggattgcgaa ctattgatgg taaaaaatat tactttaata ctaacactgc tgttgcagtt 7441 actggatggc aaactattaa tggtaaaaaa tactacttta atactaacac ttctatagct 7501 tcaactggtt atacaattat tagtggtaaa catttttatt ttaatactga tggtattatg 7561 cagataggag tgtttaaagg acctgatgga tttgaatact ttgcacctgc taatacagat 7621 gctaacaata tagaaggtca agctatacgt tatcaaaata gattcctata tttacatgac 7681 aatatatatt attttggtaa taattcaaaa gcagctactg gttgggtaac tattgatggt 7741 aatagatatt acttcgagcc taatacagct atgggtgcga atggttataa aactattgat 7801 aataaaaatt tttactttag aaatggttta cctcagatag gagtgtttaa agggtctaat 7861 ggatttgaat actttgcacc tgctaatacg gatgctaaca atatagaagg tcaagctata 7921 cgttatcaaa atagattcct acatttactt ggaaaaatat attactttgg taataattca 7981 aaagcagtta ctggatggca aactattaat ggtaaagtat attactttat gcctgatact 8041 gctatggctg cagctggtgg acttttcgag attgatggtg ttatatattt ctttggtgtt 8101 gatggagtaa aagcccctgg gatatatggc taa

(28) TcdB is encoded by the tcdB gene. Sequences for TcdB are known for a number of species, e.g., for C. difficile 630 (the TcdB NCBI Gene ID is 4914074) and polypeptide sequence (e.g., YP_001087135.1 (SEQ ID NO: 3). The sequence for the TcdB gene product is as follows (SEQ ID NO: 3):

(29) TABLE-US-00003 (SEQ ID No: 3)    1 mslvnrkqle kmanvrfrtq edeyvailda leeyhnmsen tvvekylklk dinsltdiyi   61 dtykksgrnk alkkfkeylv tevlelknnn ltpveknlhf vwiggqindt ainyinqwkd  121 vnsdynvnvf ydsnaflint lkktvvesai ndtlesfren lndprfdynk ffrkrmeiiy  181 dkqknfinyy kaqreenpel iiddivktyl sneyskeide lntyieesln kitqnsgndv  241 rnfeefknge sfnlyeqelv erwnlaaasd ilrisalkei ggmyldvdml pgiqpdlfes  301 iekpssvtvd fwemtkleai mkykeyipey tsehfdmlde evqssfesvl asksdkseif  361 sslgdmeasp levkiafnsk giinqglisv kdsycsnliv kqienrykil nnslnpaise  421 dndfntttnt fidsimaean adngrfmmel gkylrvgffp dvkttinlsg peayaaayqd  481 llmfkegsmn ihlieadlrn feisktnisq steqemaslw sfddarakaq feeykrnyfe  541 gslgeddnld fsqnivvdke yllekissla rssergyihy ivqlqgdkis yeaacnlfak  601 tpydsvlfqk niedseiayy ynpgdgeiqe idkykipsii sdrpkikltf ighgkdefnt  661 difagfdvds lsteieaaid lakedispks ieinllgcnm fsysinveet ypgklllkvk  721 dkiselmpsi sqdsiivsan qyevrinseg rrelldhsge winkeesiik disskeyisf  781 npkenkitvk sknlpelstl lqeirnnsns sdieleekvm lteceinvis nidtqiveer  841 ieeaknltsd sinyikdefk liesisdalc dlkqqneled shfisfedis etdegfsirf  901 inketgesif vetektifse yanhiteeis kikgtifdtv ngklvkkvnl dtthevntln  961 aaffiqslie ynsskeslsn lsvamkvqvy aqlfstglnt itdaakvvel vstaldetid 1021 llptlseglp iiatiidgvs lgaaikelse tsdpllrqei eakigimavn lttattaiit 1081 sslgiasgfs illvplagis agipslvnne lvlrdkatkv vdyfkhvslv etegvftlld 1141 dkimmpqddl viseidfnnn sivlgkceiw rmeggsghtv tddidhffsa psityrephl 1201 siydvlevqk eeldlskdlm vlpnapnrvf awetgwtpgl rslendgtkl ldrirdnyeg 1261 efywryfafi adalittlkp ryedtnirin ldsntrsfiv piitteyire klsysfygsg 1321 gtyalslsqy nmginielse sdvwiidvdn vvrdvtiesd kikkgdlieg ilstlsieen 1381 kiilnshein fsgevngsng fvsltfsile ginaiievdl lsksykllis gelkilmlns 1441 nhiqqkidyi gfnselqkni pysfvdsegk engfingstk eglfvselpd vvliskvymd 1501 dskpsfgyys nnlkdvkvit kdnvniltgy ylkddikisl sltlqdekti klnsvhldes 1561 gvaeilkfmn rkgntntsds lmsflesmni ksifvnflqs nikfildanf iisgttsigq 1621 feficdendn iqpyfikfnt letnytlyvg nrqnmivepn ydlddsgdis stvinfsqky 1681 lygidscvnk vvispniytd einitpvyet nntypevivl danyinekin vnindlsiry 1741 vwsndgndfi lmstseenkv sqvkirfvnv fkdktlankl sfnfsdkqdv pvseiilsft 1801 psyyedglig ydlglvslyn ekfyinnfgm mvsgliyind slyyfkppvn nlitgfvtvg 1861 ddkyyfnpin ggaasigeti iddknyyfnq sgvlqtgvfs tedgfkyfap antldenleg 1921 eaidftgkli ideniyyfdd nyrgavewke ldgemhyfsp etgkafkgln qigdykyyfn 1981 sdgvmqkgfv sindnkhyfd dsgvmkvgyt eidgkhfyfa engemqigvf ntedgfkyfa 2041 hhnedlgnee geeisysgil nfnnkiyyfd dsftavvgwk dledgskyyf dedtaeayig 2101 lslindgqyy fnddgimqvg fvtindkvfy fsdsgiiesg vqniddnyfy iddngivqig 2161 vfdtsdgyky fapantvndn iygqaveysg lvrvgedvyy fgetytietg wiydmenesd 2221 kyyfnpetkk ackginlidd ikyyfdekgi mrtglisfen nnyyfnenge mqfgyinied 2281 kmfyfgedgv mqigvfntpd gfkyfahqnt ldenfegesi nytgwldlde kryyftdeyi 2341 aatgsviidg eeyyfdpdta qlvise

(30) The tcdB gene sequence for C. difficile 630 is as follows (SEQ ID NO: 4):

(31) TABLE-US-00004 (SEQ ID NO: 4)    1 atgagtttag ttaatagaaa acagttagaa aaaatggcaa atgtaagatt tcgtactcaa   61 gaagatgaat atgttgcaat attggatgct ttagaagaat atcataatat gtcagagaat  121 actgtagtcg aaaaatattt aaaattaaaa gatataaata gtttaacaga tatttatata  181 gatacatata aaaaatctgg tagaaataaa gccttaaaaa aatttaagga atatctagtt  241 acagaagtat tagagctaaa gaataataat ttaactccag ttgagaaaaa tttacatttt  301 gtttggattg gaggtcaaat aaatgacact gctattaatt atataaatca atggaaagat  361 gtaaatagtg attataatgt taatgttttt tatgatagta atgcattttt gataaacaca  421 ttgaaaaaaa ctgtagtaga atcagcaata aatgatacac ttgaatcatt tagagaaaac  481 ttaaatgacc ctagatttga ctataataaa ttcttcagaa aacgtatgga aataatttat  541 gataaacaga aaaatttcat aaactactat aaagctcaaa gagaagaaaa tcctgaactt  601 ataattgatg atattgtaaa gacatatctt tcaaatgagt attcaaagga gatagatgaa  661 cttaatacct atattgaaga atccttaaat aaaattacac agaatagtgg aaatgatgtt  721 agaaactttg aagaatttaa aaatggagag tcattcaact tatatgaaca agagttggta  781 gaaaggtgga atttagctgc tgcttctgac atattaagaa tatctgcatt aaaagaaatt  841 ggtggtatgt atttagatgt tgatatgtta ccaggaatac aaccagactt atttgagtct  901 atagagaaac ctagttcagt aacagtggat ttttgggaaa tgacaaagtt agaagctata  961 atgaaataca aagaatatat accagaatat acctcagaac attttgacat gttagacgaa 1021 gaagttcaaa gtagttttga atctgttcta gcttctaagt cagataaatc agaaatattc 1081 tcatcacttg gtgatatgga ggcatcacca ctagaagtta aaattgcatt taatagtaag 1141 ggtattataa atcaagggct aatttctgtg aaagactcat attgtagcaa tttaatagta 1201 aaacaaatcg agaatagata taaaatattg aataatagtt taaatccagc tattagcgag 1261 gataatgatt ttaatactac aacgaatacc tttattgata gtataatggc tgaagctaat 1321 gcagataatg gtagatttat gatggaacta ggaaagtatt taagagttgg tttcttccca 1381 gatgttaaaa ctactattaa cttaagtggc cctgaagcat atgcggcagc ttatcaagat 1441 ttattaatgt ttaaagaagg cagtatgaat atccatttga tagaagctga tttaagaaac 1501 tttgaaatct ctaaaactaa tatttctcaa tcaactgaac aagaaatggc tagcttatgg 1561 tcatttgacg atgcaagagc taaagctcaa tttgaagaat ataaaaggaa ttattttgaa 1621 ggttctcttg gtgaagatga taatcttgat ttttctcaaa atatagtagt tgacaaggag 1681 tatcttttag aaaaaatatc ttcattagca agaagttcag agagaggata tatacactat 1741 attgttcagt tacaaggaga taaaattagt tatgaagcag catgtaactt atttgcaaag 1801 actccttatg atagtgtact gtttcagaaa aatatagaag attcagaaat tgcatattat 1861 tataatcctg gagatggtga aatacaagaa atagacaagt ataaaattcc aagtataatt 1921 tctgatagac ctaagattaa attaacattt attggtcatg gtaaagatga atttaatact 1981 gatatatttg caggttttga tgtagattca ttatccacag aaatagaagc agcaatagat 2041 ttagctaaag aggatatttc tcctaagtca atagaaataa atttattagg atgtaatatg 2101 tttagctact ctatcaacgt agaggagact tatcctggaa aattattact taaagttaaa 2161 gataaaatat cagaattaat gccatctata agtcaagact ctattatagt aagtgcaaat 2221 caatatgaag ttagaataaa tagtgaagga agaagagaat tattggatca ttctggtgaa 2281 tggataaata aagaagaaag tattataaag gatatttcat caaaagaata tatatcattt 2341 aatcctaaag aaaataaaat tacagtaaaa tctaaaaatt tacctgagct atctacatta 2401 ttacaagaaa ttagaaataa ttctaattca agtgatattg aactagaaga aaaagtaatg 2461 ttaacagaat gtgagataaa tgttatttca aatatagata cgcaaattgt tgaggaaagg 2521 attgaagaag ctaagaattt aacttctgac tctattaatt atataaaaga tgaatttaaa 2581 ctaatagaat ctatttctga tgcactatgt gacttaaaac aacagaatga attagaagat 2641 tctcatttta tatcttttga ggacatatca gagactgatg agggatttag tataagattt 2701 attaataaag aaactggaga atctatattt gtagaaactg aaaaaacaat attctctgaa 2761 tatgctaatc atataactga agagatttct aagataaaag gtactatatt tgatactgta 2821 aatggtaagt tagtaaaaaa agtaaattta gatactacac acgaagtaaa tactttaaat 2881 gctgcatttt ttatacaatc attaatagaa tataatagtt ctaaagaatc tcttagtaat 2941 ttaagtgtag caatgaaagt ccaagtttac gctcaattat ttagtactgg tttaaatact 3001 attacagatg cagccaaagt tgttgaatta gtatcaactg cattagatga aactatagac 3061 ttacttccta cattatctga aggattacct ataattgcaa ctattataga tggtgtaagt 3121 ttaggtgcag caatcaaaga gctaagtgaa acgagtgacc cattattaag acaagaaata 3181 gaagctaaga taggtataat ggcagtaaat ttaacaacag ctacaactgc aatcattact 3241 tcatctttgg ggatagctag tggatttagt atacttttag ttcctttagc aggaatttca 3301 gcaggtatac caagcttagt aaacaatgaa cttgtacttc gagataaggc aacaaaggtt 3361 gtagattatt ttaaacatgt ttcattagtt gaaactgaag gagtatttac tttattagat 3421 gataaaataa tgatgccaca agatgattta gtgatatcag aaatagattt taataataat 3481 tcaatagttt taggtaaatg tgaaatctgg agaatggaag gtggttcagg tcatactgta 3541 actgatgata tagatcactt cttttcagca ccatcaataa catatagaga gccacactta 3601 tctatatatg acgtattgga agtacaaaaa gaagaacttg atttgtcaaa agatttaatg 3661 gtattaccta atgctccaaa tagagtattt gcttgggaaa caggatggac accaggttta 3721 agaagcttag aaaatgatgg cacaaaactg ttagaccgta taagagataa ctatgaaggt 3781 gagttttatt ggagatattt tgcttttata gctgatgctt taataacaac attaaaacca 3841 agatatgaag atactaatat aagaataaat ttagatagta atactagaag ttttatagtt 3901 ccaataataa ctacagaata tataagagaa aaattatcat attctttcta tggttcagga 3961 ggaacttatg cattgtctct ttctcaatat aatatgggta taaatataga attaagtgaa 4021 agtgatgttt ggattataga tgttgataat gttgtgagag atgtaactat agaatctgat 4081 aaaattaaaa aaggtgattt aatagaaggt attttatcta cactaagtat tgaagagaat 4141 aaaattatct taaatagcca tgagattaat ttttctggtg aggtaaatgg aagtaatgga 4201 tttgtttctt taacattttc aattttagaa ggaataaatg caattataga agttgattta 4261 ttatctaaat catataaatt acttatttct ggcgaattaa aaatattgat gttaaattca 4321 aatcatattc aacagaaaat agattatata ggattcaata gcgaattaca gaaaaatata 4381 ccatatagct ttgtagatag tgaaggaaaa gagaatggtt ttattaatgg ttcaacaaaa 4441 gaaggtttat ttgtatctga attacctgat gtagttctta taagtaaggt ttatatggat 4501 gatagtaagc cttcatttgg atattatagt aataatttga aagatgtcaa agttataact 4561 aaagataatg ttaatatatt aacaggttat tatcttaagg atgatataaa aatctctctt 4621 tctttgactc tacaagatga aaaaactata aagttaaata gtgtgcattt agatgaaagt 4681 ggagtagctg agattttgaa gttcatgaat agaaaaggta atacaaatac ttcagattct 4741 ttaatgagct ttttagaaag tatgaatata aaaagtattt tcgttaattt cttacaatct 4801 aatattaagt ttatattaga tgctaatttt ataataagtg gtactacttc tattggccaa 4861 tttgagttta tttgtgatga aaatgataat atacaaccat atttcattaa gtttaataca 4921 ctagaaacta attatacttt atatgtagga aatagacaaa atatgatagt ggaaccaaat 4981 tatgatttag atgattctgg agatatatct tcaactgtta tcaatttctc tcaaaagtat 5041 ctttatggaa tagacagttg tgttaataaa gttgtaattt caccaaatat ttatacagat 5101 gaaataaata taacgcctgt atatgaaaca aataatactt atccagaagt tattgtatta 5161 gatgcaaatt atataaatga aaaaataaat gttaatatca atgatctatc tatacgatat 5221 gtatggagta atgatggtaa tgattttatt cttatgtcaa ctagtgaaga aaataaggtg 5281 tcacaagtta aaataagatt cgttaatgtt tttaaagata agactttggc aaataagcta 5341 tcttttaact ttagtgataa acaagatgta cctgtaagtg aaataatctt atcatttaca 5401 ccttcatatt atgaggatgg attgattggc tatgatttgg gtctagtttc tttatataat 5461 gagaaatttt atattaataa ctttggaatg atggtatctg gattaatata tattaatgat 5521 tcattatatt attttaaacc accagtaaat aatttgataa ctggatttgt gactgtaggc 5581 gatgataaat actactttaa tccaattaat ggtggagctg cttcaattgg agagacaata 5641 attgatgaca aaaattatta tttcaaccaa agtggagtgt tacaaacagg tgtatttagt 5701 acagaagatg gatttaaata ttttgcccca gctaatacac ttgatgaaaa cctagaagga 5761 gaagcaattg attttactgg aaaattaatt attgacgaaa atatttatta ttttgatgat 5821 aattatagag gagctgtaga atggaaagaa ttagatggtg aaatgcacta ttttagccca 5881 gaaacaggta aagcttttaa aggtctaaat caaataggtg attataaata ctatttcaat 5941 tctgatggag ttatgcaaaa aggatttgtt agtataaatg ataataaaca ctattttgat 6001 gattctggtg ttatgaaagt aggttacact gaaatagatg gcaagcattt ctactttgct 6061 gaaaacggag aaatgcaaat aggagtattt aatacagaag atggatttaa atattttgct 6121 catcataatg aagatttagg aaatgaagaa ggtgaagaaa tctcatattc tggtatatta 6181 aatttcaata ataaaattta ctattttgat gattcattta cagctgtagt tggatggaaa 6241 gatttagagg atggttcaaa gtattatttt gatgaagata cagcagaagc atatataggt 6301 ttgtcattaa taaatgatgg tcaatattat tttaatgatg atggaattat gcaagttgga 6361 tttgtcacta taaatgataa agtcttctac ttctctgact ctggaattat agaatctgga 6421 gtacaaaaca tagatgacaa ttatttctat atagatgata atggtatagt tcaaattggt 6481 gtatttgata cttcagatgg atataaatat tttgcacctg ctaatactgt aaatgataat 6541 atttacggac aagcagttga atatagtggt ttagttagag ttggtgaaga tgtatattat 6601 tttggagaaa catatacaat tgagactgga tggatatatg atatggaaaa tgaaagtgat 6661 aaatattatt tcaatccaga aactaaaaaa gcatgcaaag gtattaattt aattgatgat 6721 ataaaatatt attttgatga gaagggcata atgagaacgg gtcttatatc atttgaaaat 6781 aataattatt actttaatga gaatggtgaa atgcaatttg gttatataaa tatagaagat 6841 aagatgttct attttggtga agatggtgtc atgcagattg gagtatttaa tacaccagat 6901 ggatttaaat actttgcaca tcaaaatact ttggatgaga attttgaggg agaatcaata 6961 aactatactg gttggttaga tttagatgaa aagagatatt attttacaga tgaatatatt 7021 gcagcaactg gttcagttat tattgatggt gaggagtatt attttgatcc tgatacagct 7081 caattagtga ttagtgaata g

(32) Outbreaks of CDI have been reported with Toxin A-negative/Toxin B-positive strains, which indicates that Toxin B is also capable of playing a key role in the disease pathology. TcdA and TcdB are 308 and 270 kDa proteins, respectively. The toxins belong to the family of large clostridial toxins (LCTs), which are a group of homologous, high molecular weight proteins that further include the lethal and hemorrhagic toxins from C. sordellii (TcsL and TcsH, respectively), α-toxin from C. novyi (Tcnα) and a cytotoxin from C. perfringens (TpeL). The homologous proteins intoxicate host cells through a multistep mechanism that involves (i) receptor binding and endocytosis, (ii) pore formation and translocation of the GTD across the endosomal membrane, (iii) autoprocessing and release of GTD into the cytosol, and (iv) glucosylation of host Rho GTPase. Both Toxins A and B also contain a second enzyme activity in the form of a cysteine protease which appears to play a role in the release of the effector domain into the cytosol after translocation. The C. difficile binary toxin modifies cell actin by a mechanism which involves the transfer of an ADP-ribose moiety from NAD onto its target protein. Given the similarities in toxin structure and the genetic similarities of Clostridial species, it is likely that the expression of toxins of other spore-forming toxigenic Clostridium species are regulated in a similar manner to that of C. difficile, i.e., in a manner sensitive to environmental conditions that can be influenced by commensal bacteria as described herein.

(33) Additional bacterial toxins, including additional Clostridial toxins, are described in Table 1.

(34) TABLE-US-00005 TABLE 1 Bacterial toxins and their mechanism of action. Toxin Organism/Result of Gram stain Mechanism Clinical Features Toxin A/toxin B Clostridium difficile Inhibits cytoskeletal Diarrhea, vomiting (gram-positive) action in epithelial cells Anthrax toxins Bacillus anthracis Adenylyl cyclase (EF), Edema and skin necrosis; shock (edema toxin [EF], (gram-positive) metalloprotease (LF) lethal toxin [LF]) Adenylate cyclase toxin Bordetella pertussis Adenylyl cyclase Tracheobronchitis (gram-negative) Botulinum toxins Clostridium botulinum Blocks release of acetylcholine, Muscle paralysis, botulism (C2/C3 toxin) (gram-positive) ADP-ribosyltransferase Lecithinase Clostridium perfringens Phospholipase Gangrene; destraction of phagocytes (α-toxin; perfringolysin O) (gram-positive) Tetanus toxin Clostridium tetani Blocks release of Spasms and rigidity of the (gram-positive) inhibitory voluntary muscles; neurotransmitters characteristic symptom of “lockjaw” Diphtheria toxin Corynebacterium diphtheria ADP-ribosylates Respiratory infection; (gram-positive) EF-2, inhibiting complicating myocarditis with protein synthesis accompanying neurologic toxicity CNF-1, CNF-2 Escherichia coli Affects ρ-GTP-binding regulators Diarrhea (gram-negative) Heat-stable toxin Escherichia coli Secondary message regulation Diarrhea (gram-negative) Hemolysin Escherichia coli Heptameric pore-forming complex Urinary tract infections (gram-negative) (hemolysin) Shiga-like toxin Escherichia coli Stops host protein synthesis Hemolytic-uremic syndrome, dysentery (gram-negative) Exotoxin A Pseudomonas aeruginosa ADP-ribosylates elongation Respiratory distress; possible (gram-negative) factor-2 (EF-2), role as virulence factor in lung inhibiting protein synthesis infections of cystic fibrosis patients Shiga toxin Shigella dysenteriae Stops host protein synthesis Dysentery (gram-negative) α-Toxin Staphylococcus aureus Heptameric pore-forming complex Abscess formation (gram-positive) (hemolysin) Toxic shock syndrome toxin 1 Staphylococcus aureus Superantigen activates T-cell Cytokine cascade elicits (TSST-1) (gram-positive) populations, cross-linking shock; capillary leak V.sub.βTCR and class II MHC syndrome and hypotension Pneumolysin Streptococcus pneumonia Pore-forming complex Pneumonia (gram-positive) (hemolysin) Pyrogenic exotoxin Streptococcus pyogenes Superantigen activates T-cell Cytokine cascade elicits (gram-positive) populations, cross-linking shock; capillary leak V.sub.βTCR and class II MHC syndrome and hypotension Streptolysin O Streptococcus pyogenes Pore-forming complex “Strep” throat, scarlet fever (gram-positive) (hemolysin) Cholera toxin Vibrio cholera Disrupts adenylyl cyclase Watery diarrhea, loss of (gram-negative) electrolytes and fluids Abbreviations used: ADP, adenosine diphosphate; EF, elongation factor; LF, lethal factor; GTP, guanosine triphosphate; TCR, T-cell receptor; MHC, major histocompatability complex
Regulation of C. difficile Toxin Gene Expression

(35) C. difficile's pathogenicity locus, PaLoc, contains the toxin operon with genes tcdA, tcdB and tcdE that respectively encode the A and B portions of the toxin and a putative holin involved in toxin export. In addition to the toxins TcdA and TcdB, the PaLoc in pathogenic strains encodes TcdR, a member of the extracytoplasmic function family of alternative sigma factors that plays a critical role in activating the expression of tcdA and tcdB; transcription of the tcdA and tcdB genes requires TcdR to enable RNA polymerase to have specificity to bind the toxin gene promoters. Within C. difficile, multiple nutritional regulators influence PaLoc gene expression at the level of tcdR and the tcdAEB operon genes. In particular, C. difficile primarily elaborates toxin under starvation conditions to extract nutrients from the host and to also enable shedding of spores. Exogenously added glucose, amino acids—proline and leucine in particular, as well as cysteine, inhibit toxin production through codY, ccpA, rex and/or prdR activation. Exogenously added butyrate induces toxin production, while butanol does not. The symptoms of CDI correlate with the expression of TcdR. The genes encoding TcdA (tcdA) and TcdB (tcdB) are located within a 19.6-kb chromosomal region that makes up the PaLoc. The activity of TcdR is modulated by TcdC, an anti-sigma factor that destabilizes the TcdR-core RNA polymerase complex. TcdC seems to be most active in rapidly growing cells.

(36) Stickland Fermentation

(37) Stickland reactions couple metabolism of pairs of amino acids in which one amino acid, acting as an electron donor, is oxidatively deaminated or decarboxylated and a second amino acid, acting as an electron acceptor, is reduced or reductively deaminated (Stickland, L. H., Biochem. J. 28: 1746-1759 (1934). The most efficient electron donors are leucine, isoleucine, and alanine, and the most efficient acceptors are glycine, proline. Hydroxyproline is also an efficient Stickland acceptor.

(38) C. difficile, like other cluster XI species of clostridia, uses Stickland fermentations to extract energy from amino acids. Donor amino acids include the electron-rich branched chain amino acids leucine, isoleucine and valine (BCAA), aromatic amino acids phenylalanine, tyrosine and tryptophan, and acceptor amino acids glycine and proline. Cellular proline and glycine reductases transfer electrons from Stickland donor amino acids to recipients proline and glycine. The reaction consumes one NADH to one NAD+ in the reductive pathway, with release of ammonia and the branched short-chain fatty acids isocaproate, isobutyrate and isovalerate, and regenerates 2 NAD+ to NADH in the oxidative pathway. to regenerate NAD+ to NADH.

(39) The reduction of the Stickland acceptors glycine and proline is performed by two selenium-dependent reductases, glycine reductase (GR) and D-Proline reductase (PR), respectively. GR catalyzes the reductive deamination of glycine to acetyl phosphate and ammonium, and PR reductively cleaves D-proline to 5-aminovalerate. The glycine reductase and proline reductase operons, respectively, mediate these reactions. Each reductase is comprised of multiple polypeptides and is dependent upon selenocysteine residues for activity. FIG. 5A-5I show metabolites from the input donor or acceptor amino acids. In one embodiment described is that the Stickland donor amino acids proline and glycine have a powerful inhibitory effect on C. difficile toxin production.

(40) Genes encoding the C. difficile GR and PR subunits are clustered in two distinct genetic loci (grd and prd, respectively) on the chromosome of C. difficile strain 630. The grd locus contains eight genes. Two of the genes, grdA and grdB, likely encode the selenocysteine-containing subunits of GR. The seven genes of the prd operon include prdF, that encodes a d-proline racemase, and prdB, that encodes the selenium-containing subunit of PR.

(41) In one embodiment, prdR activates the proline reductase operon and represses the glycine reductase operon. prdR suppresses the expression of C. difficile toxins by inhibiting butyrate, coDY, ccpA, tcdR, and/or tcdA production. The Stickland fermentation pathway using proline as the Stickland acceptor generates NADH and the metabolite 5-aminovalerate from proline. The acetate-generating pathway generates NADH and the metabolite acetate from glycine. C. difficile consumes large amounts of NADH in the carbohydrate metabolism pathway from acetate. Therefore, acetate-generating pathways are more prone to inducing a stress response pathway, leading to the generation of butyrate, codY, ccpA, tcdR, and/or tcdA toxins.

(42) In one embodiment, the method of treating or preventing a pathology caused by expression of a bacterial toxin compromises administering at least one bacterial organism that encodes and expresses one or more of D-Proline reductase (PR), Glycine reductase (GR), thioredoxin, or choloylglycine.

(43) As noted above, the C. difficile pathogen can also utilize sugars, sugar alcohols, and ethanolamine for energy production (carbohydrate metabolism and other energy production approaches used by C. difficile are discussed further below). Toxin production in C. difficile responds to environmental conditions, including the availability of specific nutrients, temperature changes, and alteration of the redox potential. The presence of a rapidly metabolizable carbon source or certain amino acids inhibits toxin gene expression. When cells are grown in rich medium, the toxin genes are transcribed only when the cells reach stationary phase. While not wishing to be bound by theory, this is fully consistent with the discovery that protective commensal species are highly proteolytic and induce genes in C. difficile that, for example, promote the use of ethanolamine in the gut environment as an energy source.

(44) Nutritional regulators within C. difficile, including codY, ccpA, and rex sense aspects of amino acid, sugar, Stickland reactions and NAD+/NADH pools respectively. Each of these regulons also exerts effects on PaLoc gene expression through direct and indirect mechanisms.

(45) Upon binding of BCAA and GTP, codY strongly represses tcdR transcription, with subsequent reduction of tcdAEB gene expression. ccpA, active under carbon starvation conditions, binds the tcdAEB operon promoter, enhancing toxin expression if the tcdR sigma factor has been expressed. Thus, starvation where carbohydrates and Stickland amino acids are limiting induces expression of toxin. Under conditions of nutrient sufficiency, codY, ccpA and rex act coordinately through direct and indirect mechanisms to repress the expression of PaLoc genes. Notably, exogenous in vitro addition of Stickland amino acids or carbohydrate energy sources represses C. difficile toxin expression through the above mechanisms, while exogenous addition of butyrate, a key end product of anaerobic carbohydrate fermentation, can alone induce toxin expression. Together, these gene regulatory systems promote C. difficile toxin expression under conditions of starvation and energy limitation by sensing preferred sources for intracellular energy production.

(46) NAD+/NADH

(47) The balance of NAD+ to NADH influences the expression of C. difficile toxin. The Stickland reaction involves the coupled oxidation and reduction of pairs of amino acids to generate ATP and NAD+. The oxidative pathway generates ATP and NADH, while the reductive pathway regenerates NAD+ from NADH. Proline reductase (PR) and glycine reductase (GR) expression are specifically induced in the presence of proline and glycine, respectively, and carry out the respective reduction of these amino acids. Moreover, the addition of proline to the growth medium decreases the expression of GR-encoding genes, suggesting a preferential utilization of proline for NAD+ regeneration. PrdR, which is a regulator that responds to proline, mediates both the proline-dependent activation of PR and the proline-dependent repression of toxin genes and the GR operon. When proline is limiting in the medium or if PrdR or PR is inactive, the alternative reductive pathways are induced. In fact, both PrdR and a functional PR are indirectly required for the proline-dependent regulation of the alternative reductive pathways in response to the intracellular concentration of NADH and NAD+. This process involves the global redox-sensing regulator Rex. In a number of Gram-positive bacteria, Rex acts as a repressor of genes that are important for growth using fermentation. Rex directly senses changes in redox status and is only active as a DNA-binding protein when the intracellular NADH/NAD+ ratio is low. The protein Rex is stimulated by NAD+ but inhibited by NADH. Although Rex, like PrdR, controls the proline-responsive expression of these alternative reductive pathways, Rex also mediates the proline-dependent repression of toxin gene expression, probably through the regulation of butyrate production. As a result, when proline is not limiting the NADH/NAD+ ratio is low and Rex is active as a repressor of the alternative NAD+ regeneration pathways. In contrast, if proline becomes limiting, the NADH/NAD+ ratio increases and NADH prevents Rex-dependent repression of the alternative pathways. The regeneration of NAD+ using these alternative reductive pathways leads to an accumulation of butyrate, a compound that stimulates toxin synthesis as shown in FIG. 9.

(48) In one embodiment, the method of treating or preventing a pathology caused by expression of a bacterial toxin compromises administering at least one bacterial organism that promotes Stickland fermentation by C. difficile. In another embodiment, the bacterial organism itself performs Stickland fermentation—bacteria that have evolved to perform Stickland fermentation tend to express, among other things, extracellular proteolytic activities that can feed amino acids into the Stickland fermentation pathway for C. difficile.

(49) The following discusses the C. difficile toxin regulatory factors involved in sensing environmental conditions.

(50) TcdR

(51) TcdR or “alternative RNA polymerase sigma factor TcdR” is encoded by the tcdR gene. Sequences for TcdR are known for a number of species, e.g., for C. difficile 630 (the TcdR NCBI Gene ID is 4914073) and polypeptide sequence (e.g., YP_001087134.1 (SEQ ID NO: 5). The sequence for the TcdR gene product is as follows (SEQ ID NO: 5):

(52) TABLE-US-00006 (SEQ ID No: 5)   1 mqksfyeliv larnnsvddl qeilfmfkpl vkklsrvlhy eegetdliif fieliknikl  61 ssfseksdai ivkyihksll nktfelsrry skmkfnfvef denilnmknn yqsksvfeed 121 icffeyilke lsgiqrkvif ykylkgysdr eisvklkisr qavnkaknra fkkikkdyen 181 yfnl

(53) The tcdR gene sequence for C. difficile 630 is as follows (SEQ ID NO: 6):

(54) TABLE-US-00007 (SEQ ID NO: 6)   1 atgcaaaagt ctttttatga attaattgtt ttagcaagaa ataactcagt agatgatttg  61 caagaaattt tatttatgtt taagccatta gtaaaaaaac ttagtagagt tttacattat 121 gaagagggag aaacagattt aataatattt tttattgaat taataaaaaa tattaaatta 181 agtagctttt cagaaaaaag cgatgctatt atagtcaaat atattcataa atcattactg 241 aataagactt ttgagttgtc tagaagatat tctaaaatga agtttaattt tgtagaattt 301 gatgaaaata tcttaaatat gaaaaataat tatcaaagta agtctgtttt tgaggaagat 361 atttgttttt tcgaatatat tttgaaagaa ttatctggta ttcaaagaaa agttattttt 421 tataaatatt taaaaggata ttctgataga gaaatatcag tgaaattaaa aatatctaga 481 caagctgtta ataaggctaa aaatagagca tttaaaaaaa taaaaaaaga ctatgaaaat 541 tattttaact tgtaa

(55) TcdR polypeptide expression can be detected or measured via immunoassay, e.g., via an ELISA using antibodies raised against TcdR. TcdR expression can also be detected or measured by RT-PCR using primers specific for the tcdR mRNA.

(56) CodY

(57) CodY or “transcriptional repressor CodY” refers to a protein encoded by the codY gene. CodY is a sensor of carbon and nitrogen, and binds GTP and leucine to become active. When active, it represses transcription through a number of genes. C. difficile actively undergoing Stickland fermentations (abundant leucine and energy) represses toxin production in part through CodY's effects on tcdR and tcd operon gene expression. Transcription of the tcdR gene is repressed during the rapid exponential growth phase by CodY. CodY is active in cells with an excess of branched-chain amino acids (isoleucine, leucine, and valine) and GTP. When the cells reach stationary phase, the intracellular concentrations of these ligands decrease and CodY is less able to bind as a repressor, leading to derepression of tcdR transcription.

(58) Sequences for CodY are known for a number of species, e.g., for C. difficile 630 (the codY NCBI Gene ID 4915868) and polypeptide sequence (e.g., YP_001087769.1 (SEQ ID NO: 7). The sequence for the codY gene product is as follows (SEQ ID NO: 7):

(59) TABLE-US-00008 (SEQ ID No: 7)   1 masevlqktr kinktlqtsg gssvsfdlla galgdvlssn vyvvsakgkv lglhlndvqd  61 ssviedeytk qkkfsdeytq nvlkidetle nlngekilei fpeehgrlqk yttvvpilgs 121 gqrlgtlvls rysnsfnddd lviaeysatv vgleilraig eeleeemrkk avvqmaigtl 181 syseleaveh ifaeldgkeg llvaskiadr vgitrsvivn alrkfesagv iesrslgmkg 241 thirilndkl tdelkklknn q

(60) The coDY gene sequence for C. difficile 630 is as follows (SEQ ID NO: 8):

(61) TABLE-US-00009 (SEQ ID NO: 8)   1 atggcaagtg aagtgttaca aaaaacaagg aaaataaata aaacattaca aacaagtggt  61 ggaagcagtg tctcttttga tttactggcc ggagcattgg gcgacgtttt aagttctaat 121 gtttatgtag taagtgcaaa aggtaaagta ctaggtcttc atttaaatga tgttcaagac 181 agttcagtta tagaagatga gtatactaag caaaagaaat tttcagatga atatactcaa 241 aatgtgttaa aaattgatga aacattagaa aatttaaatg gtgagaagat attagaaatc 301 tttcctgaag aacatggaag attacaaaaa tatactacag tagttccaat attaggaagc 361 ggtcaaagat taggaacatt ggtactttca agatattcaa attcattcaa tgatgatgat 421 ttagtaatag ctgaatacag tgcaactgtt gttggtcttg aaatattaag agcaataggt 481 gaagaattag aagaagaaat gagaaagaaa gctgtagttc aaatggcaat aggcactctg 541 tcctactccg agcttgaagc agttgaacat atttttgctg aattggatgg aaaagaaggt 601 ctacttgtag caagtaagat agctgataga gttggtataa ctaggtctgt aatagtaaat 661 gcacttagaa aatttgagag tgcaggtgtg atagaatcaa gatcattagg tatgaaaggt 721 actcatataa gaatacttaa tgacaaactt acagatgaat taaaaaaatt aaaaaacaat 781 caataa

(62) CodY polypeptide expression can be detected or measured via immunoassay, e.g., via an ELISA using antibodies raised against CodY. CodY expression can also be detected or measured by RT-PCR using primers specific for the codY mRNA.

(63) CcpA

(64) Catabolite control protein A, CcpA, senses carbon state within the cell and is a global regulator of carbon metabolism in Gram-positive bacteria. In B. subtilis, fructose derivatives of glucose bind and activate CcpA. Regulation of C. difficile toxin production by carbon source is mediated at least in part by CcpA, which is a direct repressor of the tcdA and tcdB genes.

(65) CcpA protein is encoded by the ccpA gene. Sequences for CcpA are known for a number of species, e.g., for C. difficile 630 (the CcpA NCBI Gene ID 4915199) and polypeptide sequence (e.g., YP_001087548.1 (SEQ ID NO: 9). The sequence for the CcpA gene product is as follows (SEQ ID NO: 9):

(66) TABLE-US-00010 (SEQ ID No: 9)   1 mkgnitikdv akqagvsist vsrvindskp vtdevkqkvl eviketgyip nplarslvtk  61 ksqligvivp evsdsfvnev lngieevakm ydydillant ysdkeqelks inllrakqve 121 givmiswive qehinyiqnc gipatyiskt arnydiytvs tsneeatfdm tehlikkghe 181 kiafimtskd dtvlemerla gyekalsnnn ieldksliky ggtdyesgyn smkellddgi 241 iphaafvtgd eaaigainai cdagykvped isvagfndvk iarmyrpklt tvyqplydmg 301 avairmvikl inkelienkk ielpyrivdr esvterkk

(67) The CcpA gene sequence for C. difficile 630 is as follows (SEQ ID NO:10):

(68) TABLE-US-00011 (SEQ ID NO: 10)   1 atgaaaggca atataacgat aaaagatgtt gctaaacaag caggagtgtc aatatctact  61 gtatctagag ttataaatga ttcaaaacct gtaactgatg aagtcaaaca aaaagtttta 121 gaggttataa aagagactgg atatatacca aatccacttg ctagaagctt agtaacaaag 181 aagagtcaat taataggggt aatagttcca gaagtttcag attcttttgt taatgaggtg 241 ttaaatggga tagaagaggt tgctaaaatg tatgactatg atattctttt agcgaataca 301 tactctgata aggaacaaga acttaagagt ataaatctat tgagagcaaa acaagtggaa 361 ggtatagtta tgatttcatg gatagttgaa caagaacata tcaactatat acaaaattgt 421 ggaataccag cgacatatat aagtaaaact gctagaaatt atgatatata tacagtaagt 481 actagcaacg aagaagctac ttttgatatg acagagcatc ttataaagaa aggtcatgaa 541 aagatagctt ttataatgac gagtaaagat gatactgttt tagaaatgga aagacttgct 601 ggttatgaga aagcactttc aaataacaat atagaattag acaagagttt gattaagtat 661 ggtggaactg attatgagag tggatacaat agtatgaaag aactattaga tgatggaata 721 atacctcatg cggcttttgt aacaggtgat gaggctgcca taggtgctat aaatgctata 781 tgtgatgctg gatataaggt tccagaagac atatctgttg caggatttaa tgatgttaag 841 atagctagaa tgtatagacc taaacttact acagtatatc aacctctata cgatatggga 901 gcagtagcaa taagaatggt tataaaatta ataaataagg aattaattga aaataagaaa 961 atagaattac cttatagaat tgttgataga gaaagtgtta cagaaagaaa aaaataa

(69) CcpA polypeptide expression can be detected or measured via immunoassay, e.g., via an ELISA using antibodies raised against CcpA. CcpA expression can also be detected or measured by RT-PCR using primers specific for the ccpA mRNA.

(70) Rex

(71) Rex or “redox-sensing transcriptional repressor” senses energy state of the cell, particularly the concentration of NADH/NAD+. When activated by low energy (high concentrations of NAD+), Rex is known to indirectly lead to toxin expression, though the mechanisms of action are not well described. High NAD+ and butyrate levels, the latter possibly reflective of NADH consumption, are believed to promote C. difficile toxin production through this pathway.

(72) Sequences for Rex and the gene sequence encoding it are known for a number of species, e.g., for C. difficile 630 (the rex NCBI Gene ID 4914836) and polypeptide sequence (e.g., YP_001086640.1 (SEQ ID NO:11). The sequence for the Rex gene product is as follows (SEQ ID NO: 11):

(73) TABLE-US-00012 (SEQ ID NO: 11)   1 mlgnknisma virrlpkyhr ylgdlldrdi qrisskelsd iigftasqir qdlnnfggfg  61 qqgygynvea lhteigkilg ldrpynavlv gagnlgqaia nyagfrkagf eikalfdanp 121 rmiglkiref evldsdtled fiknnnidia vlcipkngaq evinrvvkag ikgvwnfapl 181 dlevpkgviv envniteslf tlsylmkegk

(74) The rex gene sequence for C. difficile 630 is as follows (SEQ ID NO:12):

(75) TABLE-US-00013 (SEQ ID NO: 12)   1 atgttgggaa ataaaaatat atcaatggca gttataagaa ggctcccaaa atatcataga  61 tatcttggag acttattaga tagggatata caaagaatat cttctaaaga attgagtgat 121 ataatagggt ttaccgcttc tcaaataaga caagatttaa acaactttgg tggatttgga 181 caacaaggat atggttataa tgtagaagct cttcatactg agataggtaa aattcttggg 241 ttggatcgac catacaacgc agttcttgta ggagcaggta acttaggaca agctatagcc 301 aattatgcag gatttagaaa agctggattc gagataaaag ctttatttga tgcaaatcct 361 agaatgatag gtttaaagat aagagagttt gaagtattag attcagatac tttagaagac 421 tttataaaaa acaataatat agatattgct gtattatgta tacctaaaaa tggagcacaa 481 gaagttatta atagagttgt aaaagctgga atcaaaggtg tatggaattt tgcaccttta 541 gatttagaag ttccgaaagg tgttatagtt gaaaatgtaa acttaacaga aagtttattt 601 accttatcgt atttaatgaa agaaggaaag tag

(76) Rex polypeptide expression can be detected or measured via immunoassay, e.g., via an ELISA using antibodies raised against Rex. Rex expression can also be detected or measured by RT-PCR using primers specific for the rex mRNA.

(77) Energy status of C. difficile is important for determining whether the pathogen expresses toxin. The following considers various pathways in addition to Stickland fermentation that C. difficile uses to extract energy needed for metabolism from its environment.

(78) C. difficile Carbohydrate Utilization

(79) C. difficile metabolizes sugars such as glucose and fructose, and sugal alcohols such as sorbitol and mannitol for energy production. End metabolites and points of energy production are shown in FIG. 5G and in FIG. 9. Glycolytic pathways generate ATP and NADH and lead to production of pyruvate, lactate, propionate, acetate or ethanol as metabolites. The succinate pathway generates ATP and GTP and consumes NADH in the conversion of two pyruvates to succinate. Butyrate production can occur from condensation of two acetates into acetylCoA to butyrate, or from conversion of succinate to crotonylCoA to butyrylCoA and butyrate; while some ATP is produced in the process of butyrate production, substantive NADH is consumed in these pathways.

(80) C. difficile Ethanolamine Utilization

(81) Ethanolamine occurs abundantly in gut secretions, primarily from the breakdown of phosphatidyl ethanolamine from sloughed epithelial cells, as well as from dietary and other commensal sources. The C. difficile eut operons include a two-component ethanolamine sensing system and transporter, and downstream genes that encode the carboxysome, a polyhedral protein complex in which ethanolamine is metabolized to ammonia and acetaldehyde, resulting in the generation of NADH from NAD+. A schematic of the pathway is shown in FIG. 9.

(82) C. difficile Reductive Leucine Pathway

(83) C. difficile also uses the reductive leucine pathway for energy. Mediated by the had gene operon, the pathway generates 2 ATP from 3 leucine molecules. No net NADH/NAD+ is consumed, and the end product of this pathway is isocaproate.

(84) Cysteine and Threonine Use

(85) C. difficile can convert these amino acids to pyruvate with branch points for conversion of pyruvate to acetate, propionate or butyrate, that follow the glycolytic pathways.

(86) SCFA, bSCFA and 5-Aminovalerate

(87) Exogenous acetate and succinate are hypothesized to be taken up and converted to butyrate by C. difficile if it needs energy and does not have sugars or amino acids readily available. The capacity of C. difficile to use exogenous branched short-chain fatty acids and 5-aminovalerate is not known. Other organisms can use these compounds for further energy derivation. Without wishing to be bound by theory, another potential mechanism of protection provided by Stickland fermenting species could be cross-feeding these compounds to C. difficile for energy, or through other mechanisms of C. difficile sensing its extracellular environment.

(88) PrdR

(89) PrdR regulates that proline and glycine reductase enzymes, and also has indirect effects on toxin expression. With abundant proline, PrdR activates the proline reductase operon and inhibits the glycine reductase operon. PrdR activates the proline reductase operon and represses the glycine reductase operon. prdR suppresses the expression of C. difficile toxins by inhibiting butyrate, coDY, ccpA, tcdR, and/or tcdA production. The Stickland fermentation pathway using proline as the Stickland acceptor generates NADH and the metabolite 5-aminovalerate from proline. The acetate-generating pathway generates NADH and the metabolite acetate from glycine. C. difficile consumes large amounts of NADH in the carbohydrate metabolism pathway from acetate

(90) Therapeutic Microbiota

(91) Described herein are therapeutic microbiota that suppress toxin production by Gram positive, spore-forming bacteria such as C. difficile. As described herein above, commensal species that provide C. difficile with amino acids and other energy sources that promote Stickland fermentation can provide therapeutic benefits by suppressing C. difficile toxin production. Such species include, for example, species that express and secrete one or more protease enzymes that generate a supply of amino acids for C. difficile to derive energy from via Stickland fermentation, as well as species that themselves perform Stickland fermentation.

(92) Proteases Expressed by Therapeutic Species

(93) In one embodiment, a method of suppressing bacterial toxin production or treating or preventing a pathology caused by expression of a bacterial toxin compromises administering at least one bacterial organism that encodes and secretes a protease enzyme. Protease enzymes catalyze protein catabolism by hydrolysis of peptide bonds. Proteases are produced by all living organisms, in which they display many physiological functions ranging from generalized protein degradation to more specific and regulated processes such as blood coagulation, hormone activation, or transport of secretory proteins across membranes. Proteases can be either exopeptidases, whose actions are directed by the amino- or carboxyl terminus of proteins, or endopeptidases, which cleave internal peptide bonds. Extracellular proteases are made as precursors, containing an amino-terminal signal peptide, which is removed during the export to generate a mature, extracellular protease.

(94) Proteolytic Clostridia elaborate a number of extracellular and membrane-bound metalloprotein, serine and other classes of proteases. The proteases generate free amino acids from available extracellular protein. An estimated 10-15 grams/day of undigested dietary protein enters the large intestine and remains available for microbial digestion and growth. The proteolytic species commonly use Stickland fermentations as core metabolic processes for energy generation under anaerobic conditions. Protease activity can be measured biochemically with lysis assays of casein, gelatin and other proteins, and with, e.g., FITC-conjugated substrates that release the fluorophore for detection. Microbiologically, protease activity can be measured on solid agar (casein hydrolysis agar), or with casein gelatin or meat granule hydrolysis in liquid media.

(95) Among Stickland-fermenting Cluster XI Clostridia, Clostridium bifermentans is among the most highly proteolytic species, preferring Stickland fermentations over glycolytic pathways for energy extraction. In contrast, C. sardiniense, a non-proteolytic and strongly glycolytic Cluster I Clostridial species, produces abundant butyrate through anaerobic fermentation of available carbon sources.

(96) In one embodiment, a bacterial organism administered as described herein, e.g., to suppress C. difficile toxin production, encodes and secretes at least one protease selected from the group shown in Table 2 or a homologue thereof. In another embodiment, the species administered encodes and secretes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, eleven or more, twelve or more, thirteen or more, fourteen or more, or all of the protease enzymes listed in Table 2. In another embodiment, the species administered expresses one or more (up to and including all) enzymes with the same Enzyme Commission (E.C.) number as an enzyme in Table 2. That is, the administered species can express and secrete one or more enzymes that catalyze the same reaction as an enzyme listed in Table 2. Additional bacteria that express and secrete such enzymes can be identified, for example, by analysis of bacterial genomic sequences for sequence encoding such secreted enzymes. For example, the sequence encoding a representative listed C. bifermentans protease can be used to query the genomic sequences of other non-pathogenic bacteria, including but not limited to other commensal bacteria, including but not limited to other Clostridial bacteria, for sequence encoding a homologous enzyme.

(97) TABLE-US-00014 TABLE 2 Representative secreted proteases encoded by Clostridium bifermentans MHMC14 and the corresponding PATRIC (Pathosystems Resource Integration Center) ID Number (https://www.patricbrc.org/). Extracellular Proteases PATRIC ID Protease PrsW fig|186802.30.peg.279 ATP-dependent protease La fig|186802.30.peg.290 (EC 3.4.21.53) Type II Protease fig|186802.30.peg.313 ATP-dependent Zn protease fig|186802.30.peg.414 CAAX amino terminal protease fig|186802.30.peg.543 family protein CAAX amino terminal protease fig|186802.30.peg.2205 family protein CAAX amino terminal protease fig|186802.30.peg.2313 family protein Putative membrane protease YugP fig|186802.30.peg.2680 Uncharacterized zinc protease YmfH fig|186802.30.peg.2745 FIG001621: Zinc protease fig|186802.30.peg.2746 Major intracellular serine fig|186802.30.peg.830 protease precursor (EC 3.4.21.—) CAAX amino terminal protease fig|186802.30.peg.921 family protein Uncharacterized zinc protease YmxG fig|186802.30.peg.936 Serine protease, DegP/HtrA, fig|186802.30.peg.3000 do-like (EC 3.4.21.) ATP-dependent Clp protease fig|186802.30.peg.3018 ATP-binding subunit ClpX ATP-dependent Clp protease fig|186802.30.peg.3019 proteolytic subunit (EC 3.4.21.92) Tail-specific protease (EC 3.4.21.—) fig|186802.30.peg.3065

(98) In one embodiment, a bacterial organism administered as described herein, e.g., to suppress C. difficile toxin production, encodes an enzyme that participates in Stickland fermentation. Such enzymes include, for example, D-proline reductase and glycine reductase. Species that encode one or both of such enzymes can be identified, for example, by analysis of genomic sequences for sequence that encodes the enzymes.

(99) D-Proline Reductase (PR)

(100) “prdA” or “D-Proline reductase (PR)” is encoded by the prdA gene. Sequences for prdA are known for a number of species, e.g., for C. difficile 630 (the prdA NCBI Gene ID is 4916399 and polypeptide sequence e.g., YP_001089760.1), as well as for C. scindens ATCC 35704 (the prdA NCBI polypeptide sequence e.g., EDS06621.1) and for C. bifermentans ATCC 638 (the prdA NCBI polypeptide sequence e.g., EQK41327.1). Proline reductase levels can be measured, for example, via immunoassay or by measurement of RNA encoding the enzyme, e.g., via RT-PCR. The sequence for the prdA gene product for C. difficile 630 is as follows (SEQ ID NO: 13):

(101) TABLE-US-00015 (SEQ ID NO: 13)   1 msitletaqa handpavccc rfeagtiiap enledpaifa dledsgllti pengltigqv  61 lgaklketld alspmttdnv egykageake evveetveea apvseaavvp vstgvagetv 121 kihigegkni sleiplsvag qagvaapvan vaapvasaaa evapkveekk llrsltkkhf 181 kidkvefade tkiegttlyi rnaeeickea netqelvvdm kleiitpdky etyseavldi 241 qpiatkeege lgsgitrvid gavmvltgtd edgvqigefg ssegelntti mwgrpgaadk 301 geifikgqvt ikagtnmerp gplaahrafd yvtqeireal kkvdnslvvd eevieqyrre 361 gkkkvvvike imgqgamhdn lilpvepvgt lgaqpnvdlg nmpvvlsple vldggihalt 421 cigpaskems rhywreplvi ramedeeidl vgvvfvgspq vnaekfyvsk rlgmlveame 481 vdgavvtteg fgnnhidfas hieqigmrgi pvvgvsfsav qgalvvgnky mthmvdnnks 541 kqgieneils nntlapedav rimamlknai egvevkaper kwnpnvklnn ieaiekvtge 601 kivleeneqs lpmskkrrei yekden

(102) The prdA gene sequence for C. difficile 630 is as follows (SEQ ID NO:14):

(103) TABLE-US-00016 (SEQ ID NO: 14)    1 atgtcaataa ctttagaaac agctcaagcc catgcaaatg acccagcagt ttgttgttgt   61 agatttgaag cgggaacaat tatagcgcca gaaaacttag aagatccagc aatatttgca  121 gacttagagg attctggatt attaacaata ccagaaaatg gattaactat aggtcaagta  181 ctaggagcta agttaaaaga aactttagat gcactttctc caatgactac agataacgta  241 gaaggataca aagcaggaga ggctaaagaa gaagtagtag aagaaacagt agaagaagca  301 gctccagtat cagaagcagc agtagttcca gtaagcacag gagttgcagg tgaaacagtt  361 aaaatacaca taggtgaagg taagaacata agcttagaga tacctttatc agtagctggt  421 caagcaggag ttgctgctcc agtagcaaac gttgctgctc cagtggcaag tgcagcagca  481 gaagtagctc caaaagttga agaaaagaaa cttttaagaa gcttaactaa aaaacacttt  541 aaaatagata aagttgaatt tgctgatgaa actaaaatag aaggaactac tttatacatc  601 agaaacgcag aagaaatatg taaagaagct aatgaaactc aagagttagt tgtagatatg  661 aagttagaaa taataactcc tgataaatat gaaacttaca gtgaagctgt attagatata  721 caaccaatcg ctactaaaga agaaggcgaa ttaggttcag gtataactag agttatagat  781 ggagctgtaa tggtattaac tggtacagat gaagatggag ttcaaatagg tgaatttggt  841 tcttcagaag gtgagttaaa tactactata atgtggggta gaccaggtgc tgctgacaaa  901 ggtgaaatat tcatcaaagg tcaagtaaca ataaaagcag gaactaacat ggaaagacca  961 ggacctttag ctgctcaccg tgcatttgac tatgtaactc aagaaataag agaagcatta 1021 aagaaagttg acaactcttt agtagttgat gaagaagtaa tagagcaata cagaagagaa 1081 ggtaaaaaga aagttgttgt tataaaagaa ataatgggac aaggtgcaat gcatgataac 1141 ctaatattac cagttgagcc agttggtaca ttaggagctc aaccaaacgt tgacttagga 1201 aacatgccag ttgtattatc tccacttgaa gtattagatg gtggtatcca tgcattaact 1261 tgtataggac ctgcatcaaa agaaatgtca agacattact ggagagagcc attagtaata 1321 agagctatgg aagacgaaga aatagattta gtaggtgttg tatttgttgg ttctccacaa 1381 gtaaatgctg agaaattcta tgtatctaag agattaggta tgttagttga agctatggaa 1441 gttgatggag ctgtagtaac tactgaaggt ttcggaaaca accatataga tttcgcatct 1501 cacatagagc aaataggtat gagaggtata ccagtagttg gtgtaagttt ctcagctgtt 1561 caaggtgctc tagttgttgg taataaatac atgactcaca tggtagacaa caataagtct 1621 aagcaaggta tagagaatga aatattatct aacaacactt tagctccaga agatgctgtt 1681 agaataatgg ctatgcttaa aaatgctata gaaggtgtag aagttaaagc tcctgaaaga 1741 aaatggaatc caaatgttaa attaaataac atagaagcta tagaaaaagt tacaggagaa 1801 aaaatagtat tagaagagaa tgagcaatct ctaccaatga gtaagaagag aagagaaata 1861 tacgaaaaag acgaaaacta a

(104) Each reductase is comprised of multiple polypeptides of which the sequences are listed below. In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. bifermentans 638 is as follows (SEQ ID NO:15):

(105) TABLE-US-00017 (SEQ ID NO: 15) atgggtataggaccatcaactaaagaaacatcattacatcactttagaga tccgcttcttgatatagttagtaatgacaaagacatagatcttctgggga tagtagtagtaggaacacctcaggacaacaaagaaaaagaatttgttgga caaagaacagctgcatggctagaagctatgagagcagatggtgttataat ttcatgtgatgggtggggaaactcacacgtagattatgctaatactattg aagaaataggaaaaagagagatcccggtagttggacttacatttaatgga acacaagctaagtttgtagttacaaataaatatatggacacaatagtaga ttttaataaatcagacaaggggatagaaacagaagttgtcggagagaaca ctgtaagcgagttagacgcaaaaaaatcattagccttattaaaattaaaa atgcaaagaaataataaaaaataa

(106) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. bifermentans 638 is as follows (SEQ ID NO:16):

(107) TABLE-US-00018 (SEQ ID NO: 16) atgtcaataactgtagaaacagctaaagctcatgctaaagatccagcggt atgctgctgtagatttgaagctgggactgtactagaaccatcaaatttag aagatccagcaatattcgctgacttagaggattcaggattattaacaata gcagatgattgtttaacaatagagcaagttttaggagctaaactattaaa aactttagatgctttaactccaataactgctgactgtgtagaaggtgtag tagcagtagctgaagaggctaaagaagaagttaaggaagaagttaaagaa gtagcaccagttgcttcagtagctccagtatctcaaatagctccagtaaa tggacaaactataaagatacatataggtgaaggtagagatataaacttag aaatacctttaaatgtagctcaaggaatgggtgtagcaccagttgctcct gtagctgtagcagaaaatgcagaagctgtagaagttaaagctgagccagt tcaagaagctaaagcaatgagaagcttaactaaaaaacattttaaaatag aaaaagtagttttcgctgaagaaactaaaatagatggaactactttatac ttaagaactccagaagaattaactaaagaagctgtaaattcagaagaatt agttgttgatatgaagttagaaataataactccagctgaatacaacaaat acagtgaaactataatggatgttcaacctatagctgctaaagaagaagga gaaataggagaaggtgtaacaagagttatagacggagttataatgatggt aactggtactgatgaaaacggagttcaaataggtgaattcggttcttcag aaggtgtattagaaactaacataatgtggggaagaccaggtgctcctgat aaaggtgatatattcatcaaaactcaagtaacagttaaagctggtactaa catggaaagaccaggaccattagctgctcactgtgcatctgattatataa ctcaagaaataagagaagcattaaagaacgctgaagagtctttagtagtt gatactgaagaattaactcaatatagaagacctggtaagaaaaaggttgt tgtagttaaagagataatgggacaaggggcaatgcatgataacttaatat tacctgttgagccagttggaacattaggagctaaaccaaacgttgactta ggaaacgttccagtagtattatctccacttgaagtattagatggtggtat acatgcattaacttgtataggacctgcatctaaagaaaactctagacatt actggagagagccattagtaatagaagctatgcatgatgaagaaatagat ttagtaggtgttatatttgtaggatctccacaagtaaatgctgagaaatt ctatgtatctaagagattaggtatgatgatagaagctatgggtgttgatg gtgctatagtaacaactgaaggattcggaaacaaccatatagatttcgct tctcatatagagcaaataggtaagagagatgtagctgtagtaggtgtaag tttctctgctgttcaaggtgctctagttgttggtaatgaatacatgaaat acatgatagacaacaacaagtctaaacaaggtatagaaaatgaagtatta tcaaacaatacattatgcccagaagatgctgtaagatctttagcaatgtt aaagacagtaatgggtggagaagaagttaaagctgctgagagaaaatgga atgctaacgttaaattaaataacgttgaattaatagaaaaagaaactggt aagaagttagaacttgttgaaaacgagcaaactttaccaatgagtgaaaa aagaaagaatatatacgaaaaagacgctaaatag

(108) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. bifermentans 638 is as follows (SEQ ID NO:17):

(109) TABLE-US-00019 (SEQ ID NO: 17) atggaagagaaaatacttagacgtttggtaattaaaccatttcatataa ataatgttgaattcaatgaaaagttctcaataaaaaaaggtacactatc cataaacaatgactacataaatgaaattaaaaattcacatgaattaata acggacataaaattagatataatcaaaccaggagattataacaaggaaa ttaatactatcatggatataatccctatatctactaaagttttaggtag attaggtgaaggaataacacacactttaacaggtgtttatgttatgctt actggtgttgatgaagatggaagacaaatgcatgaatttggatcttcag aaggtatactttctgagcaaatggtgtttggaagatatggtactccatc tactaatgattacataattcattttgatgttacagttaaaggtgggttg ccatatgagagaaaacttccgatgatgacatttaaggcatgtgatactt ttatacaaggtataagaaatgttttaaaacagcaagacggaagagatgc tacagaaattcgtgaatattttgacaaaattagacctgacgctaaaaaa gttgtaatagtaaaacaaatagcaggtcagggtgcaatgtatgacaatc aattattttctcatgaaccaagtggtttagagggaggtacatccattat tgatatgggaaatgtaccgatgataatatcacctaatgaatacagagat ggcgccttgagagctatgacttaa

(110) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. bifermentans 638 is as follows (SEQ ID NO:18):

(111) TABLE-US-00020 (SEQ ID NO: 18) atgagccttacaacaataaaaggacttcaatctgaaatatttgtaccaat aacacctcctcctgtttggactcctgtaactaaagaactaaaggatatga ctatagctttagctacagcgtcaggtgtacatttaaaagctgataagaga ttcaacctagcaggtgactttacatttagagaaataccagacacagcaac tactgatgagatgatggtatctcacggaggatatgataacgctgatgtta ataaagatataaactgtatgttccctatagacagactacatgaattagct aaagaaggatttataaaatctgtagctccagttcatataggattcatggg tggtggtggagaccaaactaaattcactgaagaaactggtcctgaaatcg ctaaaagattaaaagatgagggagtagacggtgtagttctaacagctggc tgaggtacttgccatagaactgccgtgatcgtgcagagagcaatagaaga agctggtataccaactataataatagcagctcttcctccagtagttagac aaaacggaactccaagagcagttgctccactagttccaatgggtgctaat gctggtgaaccaaacaataaagaaatgcaaatgcatatattaagagatac tttagagcaattaatagctataccatctgctggtaagataattcaattac catacgagtatgtagctcaagtataa

(112) In one embodiment, the sequence for the prdA gene product for C. scindens 35704 is as follows (SEQ ID NO: 19):

(113) TABLE-US-00021 (SEQ ID NO: 19)   1 msitaetake handpavlcc raeagitiea anledpaifd dlvdsgllnl dgaltieevl  61 gakltktcds lcpltadvve gakaptapaa eeaeeeapaa papaaapvag paaggtlkih 121 igegkdidle ipvgalggga avaplpagae avvagaaape aageekvvrs ltrkhftite 181 vkrgpetkie gttlyiregi esevidnqel vkdfkleiit pdlyhtyset vmdvqpiatk 241 egddelgtgv trvldgvvmm ltgvdeggvq igefgssegy ldenimwnrp scpdkgeifi 301 kgniviqekt nmerrgpmaa htafdvitqe irevmkkldd slvadteelk qvrrpgkkkv 361 vivkeimgqg amhdnfilpv epvgvlgara nvdlgnvpvc vsplevldgc ihaltcigpa 421 skemsrhywr eplvlealhd pevdlcgvvf vgspqinaek fyvsrrvght vemmdadgaf 481 vttegfgnnh idfashieqi gmrgipvvgm sycavqgalv vgnkymtymv dnnkseagie 541 neilgnntlc pedavralam lktamagedv kaaekkwnpn vkstnvelie stygtkvdlv 601 eneqalpmse krrlkys

(114) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. scindens 35704 is as follows (SEQ ID NO:20):

(115) TABLE-US-00022 (SEQ ID NO: 20) ttggctgaagaggtaaaagacctgagacgtcttgtaattaaagcgttcca catgaatgatgtagagtggggtgaacataatgatattactgttgacggta atatgacagtcagtaaagaaatgattgatcagctggtggctcaggaggaa cacattgaaaaaattgatattcagattattaagccgggggatcatgaccg ttggacgaatacgattatggatatcataccgatctctacaaaggtacttg gaaaattaggggagggcattacccataccattaccggcgtatatgtaatg cttaccggcgttgacgtaaatggaaagcaatgccatgaattcggttcttc tgaggggaatctgaaagaccagctgtacttgaaccgtgcaggcacgccgg gggatgatgattacataatttcctttgatgtaacgcttgcagccggaatg gggcaggagaggcctggaccgactgccgcacatagggcgtgcgataagtt tatccagacataccgtgataagatgaagaagttcaaaggcgagaagtgta cggaacgccatgagtaccatgatgtggtaaggccgggaaagaaacgcgtc ctgatcgtaaagcaggtggcaggacagggagcaatgtatgatacgcatct gttttccaaagagccgtctggcgtagagggcggacgttcaattatcgata tgggcaatatgccgatccttgtaactccaaatgagtacagagacggtatt atccgctccatgcagtag

(116) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. scindens 35704 is as follows (SEQ ID NO:21):

(117) TABLE-US-00023 (SEQ ID No: 21) atgtcaatcacagctgaaacagcgaaagaacatgctcatgatcctgcggt attatgttgtagagccgaagcaggcattacaatcgaagctgctaatcttg aagatccggcgatctttgatgacttggtagattcaggattattgaacctg gatggtgcattgaccatcgaagaagttttgggagcaaaacttacaaaaac atgtgattctctttgcccgttaactgcagatgtagttgaaggtgcaaaag cgccgactgctccagcagcagaagaggcagaagaggaagcgccggcagca ccggcaccggctgcagcacctgtagcaggacctgcggcaggcggaacact taagatccacattggagaaggcaaggacattgatcttgagatcccagttg gagcgcttggcggcggagcagcagttgcaccattgccggcaggagcagag gcagttgttgcaggagcagcagcaccagaagcagctggagaagaaaaggt tgtaagaagtttaacaagaaaacacttcacgatcacagaggttaagagag gaccagagaccaagatcgaaggaacaactctttacatccgtgaaggcatt gagtcagaagttattgacaaccaggagcttgtaaaagatttcaaactgga aatcatcactcctgatttatatcacacatattccgagactgttatggacg ttcagccaatcgctacaaaagaaggcgatgatgaactcggaacaggtgtt acaagagtacttgacggcgttgttatgatgctgacaggtgttgacgaagg cggagttcagattggcgagttcggttcttcagaaggataccttgatgaga acattatgtggaatcgtccgagctgcccagataaaggcgagatctttatc aagggtaacatcgtaatccaggaaaagacaaacatggaacgtcgtggacc tatggctgctcatacagcatttgatgtaatcacacaggaaatccgcgaag ttatgaagaaacttgatgacagccttgttgctgatacggaagaactgaag caggttcgccgtccgggcaagaagaaagtcgttatcgttaaggaaatcat gggacagggagctatgcatgacaactttatccttcctgtagagcctgttg gcgttctaggcgcaagagctaacgtagacttaggaaacgtaccggtttgc gtatctccattggaagttcttgatggatgtatccatgcattaacatgtat cggacctgcatctaaggaaatgtccagacattactggagagagccattgg ttctggaagcattgcatgacccggaagttgacctttgcggcgttgtattt gtaggatctcctcagatcaatgctgagaaattctatgtatcccgtcgtgt aggccataccgtagaaatgatggatgctgatggagctttcgttacaacgg aaggttttggaaacaaccacatcgatttcgcaagccatatcgagcagatc ggtatgagaggaattccggttgttggcatgtcttactgtgcagttcaggg cgctctggttgttggtaacaagtatatgacatacatggttgacaataaca agtctgaagctggtatcgagaacgagattcttggtaacaatacgctttgc ccggaagatgctgttcgtgcacttgctatgcttaagactgcaatggcagg cgaagacgttaaggctgctgagaagaagtggaatccaaacgttaagtcta caaacgtagagttaattgagagcacatacggtacaaaggttgatcttgtt gaaaatgagcaggctcttccgatgagtgaaaaacgtagattaaaatacag ctaa

(118) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. scindens 35704 is as follows (SEQ ID NO:22):

(119) TABLE-US-00024 (SEQ ID NO: 22) atgaatgtaggatcaaggctgacggttaaggcgtaccctgtcacagaagt gtgctatggggaggagaaccgagtgacggtggatggccggatgacggtct gtaagaacatagcagaaaagattctggcgcaggagccattgataaaggag attgatatccgtattatcatgccggatgagcaccgacagcataccaacac ggtgatggatgtgattcctctggcaaccaaagtgctgggacgggtggggg agggcattacccataccctgacaggcgtatacgtgatccttaccggtgtg gatgagagcgggcgtcagatatgtaattttggcgccagcgacggaatact cgaggagaagattgcctgggggcgggcgggaacgccgcttaggagcgacg tgctgatctcctttgacgtggttcttaaggaaggatcctgggcggatcgt ccgggtccggaagcagcccatcgcgcctgcgatacatactgccagatatt ccgggagcagataaagaagtttaatggatacaagtgcgcggaaaagcatg tctttcaggagacgtatgagccggggaaaaaagatgtctatattgtgaaa gaagtatccgggcaaggtgccgtatacgatacccggatgttcggacatga gccttgcggattcgaaggcgggaagtctgttattgatatgggctgcatgc ctgcgctggtgacgcccaatgaatttagggatggcattatgcgcgcgatg gattag

(120) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. scindens 35704 is as follows (SEQ ID NO:23):

(121) TABLE-US-00025 (SEQ ID NO: 23) atgtctattacagcagaaactgcaaaagaacatgcaaatgacccggctgt attatgctgccgggcagaagagggcattacaatacaggcttccaacttgg aagatcctgctatttttgacgagttagtggattcagggctgctatctttg gatggctgtctgacaatcggacaagtcttaggggcaaccctgacaaagac aagcgattctttatgtccattgactgcagataacgtagggggcttcaaag aggtagttgaggaagaagagcctgcatcagagccagtcgaagaagcggta gccgcagatattaatattgggggcgcggtcaccacgatcaaaaatggaaa agttgttatttcaatcaaagaaggaaaagatatctatttagaacttcctg tttaa

(122) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. scindens 35704 is as follows (SEQ ID NO:24):

(123) TABLE-US-00026 (SEQ ID NO: 24) atgggaaatgtacagattttattacgtcagcatgttggtgcaccctgtga ggcaatcgtaaaggctggggataaggtggaaaaaggtaccttgattgcaa ctcctacaggacttggcgctaacatcttttccagcgtctatggcgtggtg gaagaagtcttggaagaccgaatcgttatcaagccggatgaagagcagaa agatgagtttgtacctattaaggaaggcagcaagcttgagatggttaagg aagccggaatcgtaggtatgggcggcgcaggattcccaactggcgtgaag attggaacggaccttcacggcggatatatcctggtaaatgctgcagaatg cgagcctggacttcgccacaatatccagcagattgaagaaaagacagata tcacaatccgcggattgaaatactgcatggagatatccaatgcggcaaaa ggaattattgctattaagaagaagaacgaaaaagcgatcgaatttctcag agaggcaatcaaggatgaagacaatatcacgatccatcttcttccggata tttacccaatgggagaggaaagagcggtagtaagagaatgcctcggaaaa ctgcttgatcctacacaacttccgtcagcagcagatgcagtcgtaatcaa ctgcgagaccctgcttcgtatcgcagaggcgatcgaacttaagaaacctt gctttagcaagaatatgacggttattggaaagattaacggtggaaacgag ccgcatgtattcatggatgttccggttggaacctgtgttgcagacatgat cgagaaggcaggcggaattgatggtacatatggcgagattatcatgggtg gagcatttactggaaagtccaccacattagacgcgcctactacgaagacg acaggcggaatcatcgttacggtagagttcccggatcttcacggagcgcc ggtaggattgcttgtctgtgcgtgcggcggaagcgaagaccgtatgcgcg aactttgcgaaaagatgaatggaaaggtcgtttctgtggcaagatgtaaa caggcggttgagccgaagccgggcgcagcgcttaagtgcgagaatcctgg aaactgtcctggacaggcacagaaatgtctgcagtttaagaaggacggcg cagagtacatcatcatcggtaactgctcagactgttccaacacagttatg ggatctgcaccaaagttaaaactgaagacattccatcagacagaccatgt gatgagaacaatcggtcatccattatacagaagactgaccgtgtccaaag aagttgaccagctgcccaacggcaaataa

(124) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. scindens 35704 is as follows (SEQ ID NO:25):

(125) TABLE-US-00027 (SEQ ID NO: 25) atgggtataggaccatcaacaaaagaaacatcattgcatcacttcaggga tccgctgctggatgtagtctcttcggatacagatctggatctgatgggaa ttatcatcgtaggaacaccggacgataatgaggataagatgcttgtagga accaggacggctgtttgggccgaggcaatgcgtgcggacggcgtaatcat ctcttcggacggatggggaaacagcgacgtggattacacgaatacatgcg agcaggtggggacgagaggcatcgcggtgacgggccttaatttcagcggt acggtagctcaatttgtagttgtaaataattacctggatggaattgtgga tatcaataagagcgcggacgggacagagaccaatgtggttggggaaaaca atatggtcgagctggattgcaaaaaggcgactgcgcttctgaaacttaag atgcgaaagaatgagaaaaagtag

(126) In one embodiment, the prdA gene (D-proline reductase (EC 1.21.4.1)) sequence for C. scindens 35704 is as follows (SEQ ID NO:26):

(127) TABLE-US-00028 (SEQ ID NO: 26) atgagtttaacggttgttaaaggtttacaatctgaaatattcgttcctat tactccaccatcagtatggactcctgtaacaaaagagttgaaagacatgt ctatcgctcttgcaacagctgccggtgttcataagaaggatcaggaaaga ttcaatcttgctggtgactttacatggagaaaaatagagaacacaacacc atctagcgaactgatggtatcccatggtggatatgataacagtgatgtta acaaagatatcaactgtatgttcccgattgacagaattcatgaattggct gctgaaggatttatcagggcttgtgctccggtacatgcaggattcatggg tggtggcggaaaccaggagaagttcaaaggcgaaactggtccggctatcg cgcagatgttcaaagaagaggacgttgacgcagtaattctcaccgctggc tgaggaacctgccaccgctctgcagtattggtgcagagagcgattgaaga agctggaattcctactattattattgcagctcttccaccagttgttcgcc agactggtactcctcgtgcagttgctccattggtacctatgggtgctaat gcaggtggaccgcacaatgttgaacagcagacacagatcgtaaaggcaac tctggagcagttagttgaaatccagacacctggaaagattgttccactgc cattcgagtatgtagctaagatttaa

(128) The sequence for the prdA gene product for C. bifermentans 638 is as follows (SEQ ID NO: 27):

(129) TABLE-US-00029 (SEQ ID NO: 27)   1 meekilrrlv ikpfhinnve fnekfsikkg tlsinndyin eiknshelit dikldiikpg  61 dynkeintim diipistkvl grlgegitht ltgvyvmltg vdedgrqmhe fgssegilse 121 qmvfgrygtp stndyiihfd vtvkgglpye rklpmmtfka cdtfiqgirn vlkqqdgrda 181 teireyfdki rpdakkvviv kqiagqgamy dnqlfsheps gleggtsiid mgnvpmiisp 241 neyrdgalra mt

(130) In some embodiments, it is useful to measure proline reductase levels or activity, e.g., as an indicator of the activity of the pathway in a sample, or, e.g., to identify a bacterial species as one that likely performs Stickland fermentation and/or can aid in suppressing C. difficile toxin expression. Measurement of proline reductase levels can be performed, for example, by immunoassay or by RT-PCR for the mRNA encoding the enzyme. Measurement of proline reductase activity can be performed, for example, with the fluorometric assay described by Jackson et al., J. Bacteriol. 188: 8487-8495 (2006), which is incorporated herein by reference. The assay follows the DTT- and d-proline-dependent production of δ-aminovaleric acid, which reacts with o-phthalaldehyde to generate a fluorescent product.

(131) The nucleic acid and polypeptide sequences for the proline reductase expressed by C. difficile 630 are NCBI Gene ID 4916399, YP_001089760.1, respectively. The nucleic acid and polypeptide sequences for the proline reductase expressed by C. scindens 35704 NCBI Gene ID 167662491 and EDS06621.1, respectively. The nucleic acid and polypeptide sequences for the proline reductase expressed by C. bifermentans 638 are NCBI Gene ID 531765064 and EQK41327.1, respectively.

(132) Glycine Reductase (GR)

(133) The activity or expression of glycine reductase is important for Stickland fermentation via the glycine reductase pathway. In some embodiments, it is useful to measure glycine reductase levels or activity, e.g., as an indicator of the activity of the pathway in a sample, or, for example, to identify a bacterial species as one that likely performs Stickland fermentation. Measurement of glycine reductase levels in a sample can be performed, for example, by immunoassay and/or via RT-PCR for the mRNA encoding the enzyme. A biochemical assay for glycine reductase activity is described, for example, by Stadtman & Davis, J Biol Chem. 266(33):22147-53 (1991).

(134) The nucleic acid and polypeptide sequences for the glycine reductase expressed by C. difficile 630 are NCBI Gene ID is 4915147 and YP_001088866.2, respectively.

(135) The “grdA” or “glycine/sarcosine/betaine reductase complex protein A” glycine reductase is encoded by the grdA gene. Sequences for grdA are known for a number of species, e.g., for C. difficile 630 (the grdA NCBI Gene ID is 4915147) and polypeptide sequence (e.g., YP_001088866.2 (SEQ ID NO: 28). The sequence for the grdA gene product is as follows (SEQ ID NO: 28):

(136) TABLE-US-00030 (SEQ ID NO: 28)   1 msllsnkkvl iigdrdgipg paieecvktv egaevvfsst ecfvutaaga mdlenqnrvk  61 daadkfgaen vvillgaaea eaaglaaetv tagdptfagp lagvalglsv yhvveepiks 121 lfdesvyedq ismmemvlev eeieeemsgi reefckf

(137) The grdA gene sequence for C. difficile 630 is as follows (SEQ ID NO:29):

(138) TABLE-US-00031 (SEQ ID NO: 29)   1 atgagtttac ttagtaataa aaaggttctt ataataggtg accgtgatgg tataccagga  61 cctgcgatag aagaatgtgt aaaaacagta gaaggagcag aggttgtttt ctcatctaca 121 gaatgctttg tctgaacagc tgctggggct atggacttag aaaatcaaaa cagagttaaa 181 gatgctgctg ataaattcgg agctgaaaat gttgtgattt tactaggtgc tgctgaagcc 241 gaagctgcag gtcttgcagc cgaaacagta actgctggag atccaacttt cgctggacca 301 cttgctggag ttgccttagg attaagtgtt taccacgttg ttgaggaacc aataaaatca 361 ttatttgatg aaagtgtata tgaagaccaa ataagtatga tggaaatggt tttagaagtt 421 gaagaaatag aagaagaaat gtctggtata agagaagaat tttgtaaatt ttaa
Defined Therapeutic Microbiota

(139) Described herein are defined therapeutic microbiota that can be administered to suppress toxin expression by Gram positive, spore forming toxigenic bacteria such as C. difficile. In one embodiment, a defined therapeutic microbiota is or consists essentially of the single species, C. bifermentans. In another embodiment, the defined therapeutic microbiota comprises, consists essentially of or consists of C. scindens. In another embodiment, the defined therapeutic microbiota consists of, consists essentially of or comprises C. bifermentans and C. scindens. Strains of these species and others that express and secrete proteolytic enzymes into their surroundings and/or themselves perform Stickland fermentation are expected to promote suppression of C. difficile toxin expression. The following describes these species in further detail.

(140) Clostridium Taxonomy: Clustering. As a starting point, species of the Genus Clostridium encompass a large number of anaerobic, spore-forming bacteria. In 1994, Collins et al. (Int. J. Systematic Biol. 44: 812-826 (1994), incorporated herein by reference) described a classification system that placed the species then known, and for which there was 16S rRNA sequence data available, into 19 “clusters,” termed Clostridium Clusters I-XIX, based upon similarities and differences in 16S rRNA sequences. This taxonomy and nomenclature has been retained to date, with some refinement, e.g., classifications of some of the larger clusters into smaller sub-clusters given alphabetic identifiers, e.g., Cluster XIVa. C. difficile is in Cluster XI.

(141) Clostridium bifermentans

(142) C. bifermentans are anaerobic, motile, Gram positive bacteria that colonize the healthy human gut, and are not commonly found to be pathogenic. C. bifermentans is a member of Clostridium Cluster XI, the same cluster as C. difficile. C. bifermentans induces the C. difficile ethanolamine pathway genes and maintains proline reductase activity, glucose and sorbitol metabolism in vivo. Through the greater than 10× repression of tcdR expression and greater than 30× suppression of toxin production, strong codY activation and repression of the PaLoc genes is indicated. The C. difficile metabolic pathways influenced by C. bifermentans are also indicated to activate ccpA, rex and prdR to also inhibit toxin production.

(143) Both C. bifermentans and C. scindens possess the enzymatic machinery for Stickland fermentations. Of the two, C. bifermentans preferentially uses Stickland fermentations over glycolytic pathways, including in the presence of glucose or other sugars (see FIG. 6A and FIG. 6B), while in vitro C. scindens is preferentially glycolytic and produces abundant acetate (FIG. 6B).

(144) A genome of C. bifermentans was sequenced as part of the Human Microbiome Project, and can be found at, e.g., accession #PRJNA212658.

(145) In one embodiment, the C. bifermentans strain is 76 (ATCC #638). The 16S rRNA gene sequence for C. bifermentans strain 76 (SEQ ID NO: 30) is as follows:

(146) TABLE-US-00032 (SEQ ID NO: 30)    1 catrgctcag gatgaacgct ggcggcgtgc ctaacacatg caagtcgagc gatctcttcg   61 gagagagcgg cggacgggtg agtaacgcgt gggtaacctg ccctgtacac acggataaca  121 taccgaaagg tatactaata cgggataaca tatgaaagtc gcatggcttt tgtatcaaag  181 ctccggcggt acaggatgga cccgcgtctg attagctagt tggtaaggta atggcttacc  241 aaggcaacga tcagtagccg acctgagagg gtgatcggcc acactggaac tgagacacgg  301 tccagactcc tacgggaggc agcagtgggg aatattgcac aatgggcgaa agcctgatgc  361 agcaacgccg cgtgagcgat gaaggccttc gggtcgtaaa gctctgtcct caaggaagat  421 aatgacggta cttgaggagg aagccccggc taactacgtg ccagcagccg cggtaatatg  481 tagggggcta gcgttatccg gaattactgg gcgtaaaggg tgcgtaggtg gttttttaag  541 tcagaagtga aaggctacgg ctcaaccgta gtaagctttt gaaactagag aacttgagtg  601 caggagagga gagtagaatt cctagtgtag cggtgaaatg cgtagatatt aggaggaata  661 ccagtagcga aggcggctct ctggactgta actgacactg aggcacgaaa gcgtggggag  721 caaacaggat tagataccct ggtagtccac gccgtaaacg atgagtacta ggtgtcgggg  781 gttacccccc tcggtgccgc actaacgcat taagtactcc gcctgggaag tacgctcgca  841 agagtgaaac tcaaaggaat ttdcggggac ccgcacaagt agcggagcat gtggtttaat  901 tcgaagcaac gcgaagaacc ttacctaagc ttgacatccc actgacctct ccctaatcgg  961 agatttccct tcggggacag tggtgacagg tggtgcatgg ttgtcgtcag ctcgtgtcgt 1021 gagatgttgg gttaagtccc gcaacgagcg caacccttgc ctttagttgc cagcattaag 1081 ttgggcactc tagagggact gccgaggata actcggagga aggtggggat gacgtcaaat 1141 catcatgccc cttatgctta gggctacaca cgtgctacaa tgggtggtac agagggttgc 1201 caagccgcga ggtggagcta atcccttaaa gccattctca gttcggattg taggctgaaa 1261 ctcgcctaca tgaagctgga gttactagta atcgcagatc agaatgctgc ggtgaatgcg 1321 ttcccgggtc ttgtacacac cgcccgtcac accatggaag ttgggggcgc ccgaagccgg 1381 ttagctaacc ttttaggaag cggccgtcga aggtgaacaa atgactgggg tgaagtcgta 1441 acaaggtanc cgtatcggaa ggtgcggcbg gatcaa

(147) In another embodiment, the C. bifermentans strain is a bacterial strain comprising a 16S rRNA sequence that is at least 97%, at least 98%, at least 99%, or more identical to the sequence of SEQ ID NO: 30. A C. bifermentans strain useful in the methods and compositions described herein should express at least 75% of the extracellular proteolytic activity of C. bifermentans strain 76 (ATCC #638) when assayed with a meat granule digestion microbiological assay as described herein. In one embodiment, the C. bifermentans strain expresses at least 80%, at least 85%, at least 90%, at least 95%, at least 100% or more of the proteolytic activity of C. bifermentans strain 76 (ATCC #638).

(148) C. bifermentans is an anaerobic bacterium that can be cultured under anaerobic and microaerophilic conditions, and thus should be cultured accordingly, e.g., in a manner that limits or inhibits the bacteria's exposure to oxygen. (C. bifermentans is described as being able to tolerate up to 8% O.sub.2— see, e.g., Leja, K., Advances in Microbiology, 2014, however, growth under substantially anaerobic conditions is readily performed). Media and conditions for C. bifermentans growth in culture are known to those of ordinary skill in the art. As examples, C. bifermentans can be cultured under anaerobic conditions in, e.g., ATCC medium 2107 modified reinforced Clostridial agar/broth or ATCC medium 260 Trypticase soy agar/broth with defibrinated sheep blood (ATCC; Manassas, Va.), or grown on, e.g., Brucella Blood agar plates.

(149) Clostridium scindens

(150) C. scindens is an anaerobic, motile bacterium often found in the human gut, as well as in the soil. C. scindens is a member of Clostridium Cluster XIVa. C. scindens produces a 7-alpha bile acid dehydratase which converts primary bile acids to secondary bile acids that are strong inhibitors of C. difficile germination. It is noted that C. bifermentans has a choloylglycine deconjugating enzyme (which removes glycine from glycine-conjugated bile acids), but genomically does not possess comparable bile salt dehydroxylating enzymes.

(151) While not wishing to be bound by theory, it is likely that at least part of the mechanism by which C. scindens promotes suppression of C. difficile infection is through bile acid metabolism to produce secondary bile acids (e.g., deoxycholic acid and lithocholic acid) that maintain an environment that is hostile to or not compatible with C. difficile and/or C. difficile infection. In this regard, C. scindens bacteria possess a complete secondary bile acid synthesis pathway, producing at least two enzymes active on the side-chain of the bile acid steroid nucleus and at least two enzymes active on the hydroxyl groups of the 7-position of bile acids. C. scindens expresses bile salt hydrolase/Choloylglycine hydrolase activity (E.C. #3.5.1.24), which catalyzes hydrolysis of the amide bond in conjugated bile salts, resulting in the release of free amino acids. This activity adds another source of free amino acid generation in the gut that can at least potentially contribute further substrate amino acids that promote Stickland fermentation.

(152) A genome of C. scindens was sequenced as part of the Human Microbiome Project, and can be found at, e.g., accession #PRJNA18175.

(153) C. scindens is an anaerobic bacterium, and thus should be cultured accordingly, e.g., in a manner the limits or inhibits the bacteria's exposure to oxygen. Media and conditions for C. scindens growth in culture are known to those of ordinary skill in the art. As examples, C. scindens can be cultured under anaerobic conditions in, e.g., ATCC medium 2107 modified reinforced Clostridial agar/broth or ATCC medium 260 Trypticase soy agar/broth with defibrinated sheep blood (ATCC; Manassas, Va.), or grown on, e.g., Brucella Blood agar plates.

(154) In one embodiment, the C. scindens strain is VPI 13733 (ATCC #35704). The 16S rRNA gene sequence for C. scindens strain VPI 13733 (SEQ ID NO: 31) is as follows:

(155) TABLE-US-00033 (SEQ ID NO: 31) gagagtttgatcctggctcaggatgaacgctggcggcgtgcctaacaca tgcaagtcgaacgaagcgcctggccccgacttcttcggaacgaggagcc ttgcgactgagtggcggacgggtgagtaacgcgtgggcaacctgccttg cactgggggataacagccagaaatggctgctaataccgcataagaccga agcgccgcatggcgcggcggccaaagccccggcggtgcaagatgggccc gcgtctgattaggtagttggcggggtaacggcccaccaagccgacgatc agtagccgacctgagagggtgaccggccacattgggactgagacacggc ccagactcctacgggaggcagcagtggggaatattgcacaatgggggaa accctgatgcagcgacgccgcgtgaaggatgaagtatttcggtatgtaa acttctatcagcagggaagaagatgacggtacctgactaagaagccccg gctaactacgtgccagcagccgcggtaatacgtagggggcaagcgttat ccggatttactgggtgtaaagggagcgtagacggcgatgcaagccagat gtgaaagcccggggctcaaccccgggactgcatttggaactgcgtggct ggagtgtcggagaggcaggcggaattcctagtgtagcggtgaaatgcgt agatattaggaggaacaccagtggcgaaggcggcctgctggacgatgac tgacgttgaggctcgaaagcgtggggagcaaacaggattagataccctg gtagtccacgccgtaaacgatgactactaggtgtcgggtggcaaggcca ttcggtgccgcagcaaacgcaataagtagtccacctggggagtacgttc gcaagaatgaaactcaaaggaattgacggggacccgcacaagcggtgga gcatgtggtttaattcgaagcaacgcgaagaaccttacctgatcttgac atcccgatgccaaagcgcgtaacgcgctctttcttcggaacatcggtga caggtggtgcatggttgtcgtcagctcgtgtcgtgagatgttgggttaa gtcccgcaacgagcgcaacccctatcttcagtagccagcattttggatg ggcactctggagagactgccagggagaacctggaggaaggtggggatga cgtcaaatcatcatgccccttatgaccagggctacacacgtgctacaat ggcgtaaacaaagggaggcgaacccgcgagggtgggcaaatcccaaaaa taacgtctcagttcggattgtagtctgcaactcgactacatgaagttgg aatcgctagtaatcgcgaatcagaatgtcgcggtgaatacgttcccggg tcttgtacacaccgcccgtcacaccatgggagtcagtaacgcccgaagc cggtgacccaacccgtaagggagggagccgtcgaaggtgggaccgataa ctggggtgaagtcgtaacaaggtagccgtatcggaaggtgcggctggat cacctccttc

(156) In another embodiment, the C. scindens strain is a bacterial strain comprising a 16S rRNA sequence that is at least 97%, at least 98%, at least 99%, or more identical to the sequence of SEQ ID NO: 1. In one embodiment, the C. scindens strain expresses at least the level of bile salt hydrolase/Choloylglycine hydrolase expressed by C. scindens strain VPI 13733 (ATCC #35704). C. scindens is also proteolytic, albeit to a lesser degree than C. bifermentans. In one embodiment, the C. scindens strain used in a defined microbiota consortium as described herein has at least the proteolytic activity of C. scindens strain VPI 13733 (ATCC #35704).

(157) Clostridium hylemonae

(158) C. hylemonae is a naturally-occurring anaerobic commensal bacterium of the human gut. As described herein below, the relative abundance of C. hylemonae has been found, in combination with that of C. scindens, to be reliably predictive of the recurrence of C. difficile infection in human patients. C. hylemonae is a member of Clostridium Cluster XIVa. The 16S rRNA gene sequence for the C. hylemonae strain (SEQ ID NO: 32) is as follows:

(159) TABLE-US-00034 (SEQ ID NO: 32) aggatgaacgctgccgccgtgcttaacacatgcaagtcgaacgaagcaa tactgtgtgaagagattagcttgctaagatcagaactttgtattgactg agtggcggacgggtgagtaacgcgtgggcaacctgccttacacaggggg ataacagctagaaatggctgctaataccgcataagacctcagtaccgca tggtagaggggtaaaaactccggtggtgtaagatgggcccgcgtctgat taggtagttggtagggtaacggcctaccaagccgacgatcagtagccga cctgagagggtgaccggccacattggactgagacacggcccaaactcct acgggaggcagcagtggggaatattgcacaatgggggaaaccctgatgc agcgacgccgcgtgaaggatgaagtatttcggtatgtaaacttctatca gcagggaagaagatgacggtacctgactaagaagccccggctaactacg tgccagcagccgcggtaatacgtagggggcaagcgttatccggatttac tgggtgtaaagggagcgtagacggcatggcaagtctgaagtgaaagccc ggggctcaaccccgggactgctttggaaactgtcaggctagagtgtcgg agaggcaagtggaattcctagtgtagcggtgaaatgcgtagatattagg aggaacaccagtggcgaagcggcttgctggacgatgactgacgttgagg ctcgaaagcgtggggagcaaacaggattagataccctggtagtccacgc cgtaaacgatgattactaggtgtcgggaagcaaagcttttcggtgccgc agccaacgcaataagtaatccacctggggagtacgttcgcaagaatgaa actcaaaggaattgacggggacccgcacaagcggtggagcatgtggttt aattcgaagcaacgcgaagaaccttacctgatcttgacatcccggtgac aaagtatgtaacgtactctttcttcggaacaccggtgacaggtggtgca tggttgtcgtcagctcgtgtcgtgagatgttgggttaagtcccgcaacg gcgcaacccttatctttagtagccagcatttgaggtgggcactctagag agactgccagggataacctggaggaaggtggggatgacgtcaaatcatc atgccccttatgaccagggctacacacgtgctacaatggcgtaaacaaa gggaagcgaccctgtgaaggcaagcaaatcccaaaaataacgtctcagt tcggattgtagtctgcaactcgactacatgaagctggaatcgctagtaa tcgcgaatcagaatgtcgcggtgaatacgttcccgggtcttgtacacac cgcccgtcacaccatggggtcagtaacgcccgaagccggtgacctaacc gcaaaggaggagccgtcgaaggtg.

(160) In one embodiment, the C. hylemonae bacterium useful in the reliable prediction of C. difficile infection recurrence or in the reliable prediction of initial C. difficile infection has a 16S rRNA gene sequence of SEQ ID NO: 32. In another embodiment, a C. hylemonae bacterium useful in the reliable prediction of C. difficile infection recurrence or in the reliable prediction of initial C. difficile infection has a 16S rRNA gene sequence at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO: 32. It is also contemplated that C. hylemonae can provide therapeutic benefit, alone, or together with one or both of C. bifermentans and C. scindens.

(161) Other potentially therapeutic Clostridial species that perform Stickland fermentation include, for example, C. cadaveris (Cluster I), and C. hiranonis, C. sticklandii, Peptostreptococcus anaerobius and C. sporogenes (Cluster XI).

(162) The outcome of the studies described herein indicates that any or all of the following can have therapeutic benefit in combatting toxin production by Gram positive, spore-forming bacteria such as C. difficile:

(163) A) Maintain metabolic and energy state in C. difficile through commensal proteolytic activity to release amino acids for Stickland fermentations (preferentially via the proline reductase pathway). Metabolites of Stickland fermentations can also be used or sensed by C. difficile through mechanisms that also reduce toxin production.

(164) B) Induce or maintain expression of the C. difficile ethanolamine utilization pathway in C. difficile to help maintain energy state.

(165) C) Prevent or limit production of butyrate by C. difficile and other commensals, to limit a stimulus of C. difficile toxin production.

(166) D) Prevent C. difficile spore germination through production of secondary bile acids by C. scindens or other species that promote or produce such products.

(167) E) Reduce biomass of C. difficile through, e.g., direct competition with C. difficile and by permitting recovery of other gut commensal species that directly compete and/or prevent spore germination through innate bile salt hydrolase activities.

(168) F) Glycine Reductase activity or expression.

(169) Defined Therapeutic Microbiota, and Compositions Comprising Them

(170) It is demonstrated herein that C. bifermentans can completely protect GF and conventional mice from otherwise fatal infection with C. difficile.

(171) In one aspect, then, described herein are compositions, including but not limited to pharmaceutical compositions, comprising an oral formulation comprising C. bifermentans bacteria. In one embodiment the C. bifermentans species is the only bacterial species in the formulation. In another embodiment, the C. bifermentans is the only Clostridial XI species in the formulation. In another embodiment, the C. bifermentans is the only Clostridial species in the formulation. In another embodiment, the C. bifermentans is the only bacterial species in the formulation. Such compositions can be used to treat or prevent C. difficile infection, including recurrent C. difficile infection, and/or toxin production.

(172) Methods for the growth or preparation of C. bifermentans bacteria are known in the art. As noted herein above, this species is an obligate anaerobe, so culture under anaerobic conditions is required. Media for culture of Clostridium species are also known in the art, and are commercially available, as also noted elsewhere herein.

(173) In another aspect, described herein is a composition, including a pharmaceutical composition, comprising C. bifermentans bacteria, wherein the C. bifermentans bacteria are in dried, viable form. Methods of drying Clostridium species in a manner that maintains viability upon re-hydration are known in the art.

(174) In another aspect, described herein is a pharmaceutical composition comprising a formulation comprising C. bifermentans bacteria, wherein the composition does not comprise Bacteroides species or Escherichia species.

(175) It is contemplated that killed or proliferatively inactive, but metabolically active C. bifermentans bacteria could have beneficial effect, e.g., if administered repeatedly. However, in each of the aspects noted above, it is preferred that the bacteria are viable as the term is used herein. In this context, the bacterial species for any of the compositions described herein can be present in vegetative, metabolically and proliferatively active forms, dried viable form, spore form, or a combination of these forms. Thus, in one embodiment, the C. bifermentans bacteria are in spore form. In another embodiment, the C. bifermentans bacteria are in metabolically active form, including, but not limited to vegetative and/or actively proliferative forms. In another embodiment, the C. bifermentans bacteria are not in spore form. In another embodiment, the C. bifermentans bacteria are present as a mixture of vegetative, metabolically active and spore forms. Methods for inducing sporulation of Clostridium species are known to those of ordinary skill in the art.

(176) Another aspect described herein provides a pharmaceutical composition comprising an oral formulation comprising a bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium. In various embodiments, the bacterial population has 16S rDNA with a sequence at least 97%, 98%, 99% or more identical to the 16S rDNA of the reference bacterium.

(177) Another aspect described herein provides a pharmaceutical composition comprising a bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium, wherein the C. bifermentans bacteria is in dried, viable form. In various embodiments, either or both of the bacterial populations has 16S rDNA with a sequence at least 97%, 98%, 99% or more identical to the 16S rDNA of the reference bacterium.

(178) Another aspect described herein provides a pharmaceutical composition comprising a formulation comprising a bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium, wherein the composition does not comprise Bacteroides species or Escherichia species. In various embodiments, the bacterial population has 16S rDNA with a sequence at least 97%, 98%, 99% or more identical to the 16S rDNA of the reference bacterium.

(179) In one embodiment of this or any other aspect described herein, the compositions described herein do not comprise viable C. sardiniense bacteria. As described herein, it was found that the presence of C. sardiniense in otherwise germ-free mice comprising pathogenic C. difficile bacteria increased the severity of the resulting C. difficile infection. Thus, in one embodiment, the technology described herein excludes C. sardiniense from a therapeutic composition as described herein.

(180) In one embodiment of this or any aspect described herein, a therapeutic microbiota composition does not comprise a Bacteroides species or Escherichia species. Bacteroides is a genus of Gam-negative, obligate anaerobic bacteria. Bacteroides species can be identified by sphingolipids in their membranes, as well as by 16S rDNA sequence. They make up a substantial proportion of the gut microbiota, and are commonly mutualistic. Escherichia species are Gram-negative, non-spore forming, facultative anaerobic bacteria from the family Enterobacteriaceae. The majority of Escherichia species are commensal gut flora, although certain Escherichia strains are human pathogens. A skilled person can identify Bacteroides and Escherichia species, e.g., using PCR-based methods to quantify 16S rDNA genetic markers, among others.

(181) In one embodiment of this or any aspect described herein, the compositions described herein do not comprise any additional viable Clostridium species. In another embodiment of any aspect described herein, the compositions described herein do not comprise any additional viable bacteria of any kind. A skilled person can identify the presence of other viable bacteria (e.g., additional Clostridium species, among others) in the composition, e.g., using anaerobic culture, and identify organisms in such culture using, for example, PCR-based methods to quantify 16S rDNA genetic markers.

(182) It is also demonstrated herein that a defined consortium of Clostridium species comprising C. scindens and C. bifermentans, as those species are defined herein, is sufficient to treat or prevent C. difficile infection, including, but not limited to recurrent C. difficile infection, and to suppress toxin production by C. difficile.

(183) In one aspect, then, described herein are compositions, including but not limited to pharmaceutical compositions, comprising an oral formulation comprising C. scindens and C. bifermentans bacteria. In another embodiment of this and all other aspects described herein that involve the C. scindens and C. bifermentans species, the only bacterial species in the formulation are C. scindens and C. bifermentans. Methods for the growth or preparation of C. scindens and C. bifermentans bacteria are known in the art. As noted herein above, these species are obligate anaerobes, so culture under anaerobic conditions is required. Media for culture of Clostridium species are also known in the art, and are commercially available, as also noted herein above.

(184) In another aspect, described herein is a composition, including a pharmaceutical composition, comprising C. scindens and C. bifermentans bacteria, wherein one or both of the C. scindens and C. bifermentans bacteria is in dried, viable form. Methods of drying Clostridium species in a manner that maintains viability upon re-hydration are known in the art.

(185) In another aspect, described herein is a pharmaceutical composition comprising a formulation comprising C. scindens and C. bifermentans bacteria, wherein the composition does not comprise Bacteroides species or Escherichia species.

(186) It is contemplated that killed or proliferatively inactive, but metabolically active bacteria of these species could have beneficial effect if administered repeatedly. However, in each of the aspects noted above, it is preferred that the bacteria are viable as the term is used herein. In this context, the bacterial species for any of the compositions described herein can be present in vegetative, metabolically and proliferatively active forms, dried viable form, spore form, or a combination of these forms. Thus, in one embodiment, both of the C. scindens and C. bifermentans bacteria are in spore form. In another embodiment, both of the C. scindens and C. bifermentans bacteria are in metabolically active form, including, but not limited to vegetative and/or actively proliferative forms. In another embodiment, one or both of the C. scindens and C. bifermentans bacteria are not in spore form. In another embodiment, the C. scindens and C. bifermentans bacteria are present as a mixture of vegetative, metabolically active and spore forms. Methods for inducing sporulation of Clostridium species are known to those of ordinary skill in the art.

(187) Another aspect described herein provides a pharmaceutical composition comprising an oral formulation comprising a first bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. scindens bacterium, and a second bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium. In various embodiments, either or both of the bacterial populations has 16S rDNA with a sequence at least 97%, 98%, 99% or more identical to the 16S rDNA of the reference bacterium.

(188) Another aspect described herein provides a pharmaceutical composition comprising a first bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. scindens bacterium, and a second bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium, wherein one or both of the C. scindens and C. bifermentans bacteria is in dried, viable form. In various embodiments, either or both of the bacterial populations has 16S rDNA with a sequence at least 97%, 98%, 99% or more identical to the 16S rDNA of the reference bacterium.

(189) Another aspect described herein provides a pharmaceutical composition comprising a formulation comprising a first bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. scindens bacterium, and a second bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium wherein the composition does not comprise Bacteroides species or Escherichia species. In various embodiments, either or both of the bacterial populations has 16S rDNA with a sequence at least 97%, 98%, 99% or more identical to the 16S rDNA of the reference bacterium.

(190) The above bacterial compositions can include, for example but are not limited to metabolically active bacteria, wet bacteria, dry viable bacteria (e.g., preparations including viable spray-dried cells, freeze-dried cells, vacuum-dried cells, drum-dried cells, vitrified etc.), and the like. Preparations of Clostridium species described herein can include, for example, suspensions of Clostridium bacteria, cultured cells of Clostridium bacteria (including bacterial cells, and optionally, supernatant and medium ingredients), and, for example, Clostridium culture biomass, removed from suspension culture, e.g., by centrifugation, filtration, or the like. While viable Clostridium bacteria are used in most applications considered herein, it is contemplated that in some embodiments, processed cells of Clostridium bacteria can include, for example, ground cells, crushed cells, liquefied cells (extracts etc.) and concentrates and preparations thereof, and the like.

(191) Dried preservation removes water from the culture by evaporation (in the case of spray drying or ‘cool drying’) or by sublimation (e.g., for freeze drying, spray freeze drying). Removal of water improves long-term bacterial composition storage stability at temperatures elevated above cryogenic. If the bacterial composition comprises spore forming species and results in the production of spores, the final composition can be purified by additional means such as density gradient centrifugation.

(192) Species effective for treatments as described herein are readily available. However, to maintain strain integrity over time, bacterial composition banking can be done by culturing and preserving the strains individually, or by mixing the strains together to create a combined bank. As an example of cryopreservation, a bacterial composition culture can be harvested by centrifugation to pellet the cells from the culture medium, the supernate decanted and replaced with fresh culture broth containing 15% glycerol. The culture can then be aliquoted into 1 mL cryotubes, sealed, and placed at −80° C. for long-term viability retention. This procedure achieves acceptable viability upon recovery from frozen storage.

(193) C. bifermentans and/or C. scindens can be in spore form or not in spore form in the compositions described herein. Bacterial spores are dormant, non-reproductive structures produced by certain bacteria from the Firmicute phylum, for example in an environment lacking nutrients. Spores can be preserved as described above, and can be reactivated, e.g., by heating the endospore. In addition, C. bifermentans and/or C. scindens can be present in a mixture of metabolically active bacteria and spores. Metabolically active bacteria can actively metabolize nutrients, and will have little lag time from administration to active participation in treating or preventing C. difficile infection. They will also likely have little lag time in beginning to proliferate in the gut if conditions are appropriate.

(194) In one embodiment, any of the defined therapeutic microbiota compositions described herein further comprises a prebiotic. Prebiotics promote the growth, survival, and activity of beneficial microorganisms, or probiotics. Prebiotics have been shown to alter the compositions of microorganisms (microflora) in the gut microbiota, alone or in combination with probiotic organisms. In addition, prebiotics have been shown to increase calcium and magnesium absorption in the gut, increase bone density, enhance the immune system, reduce blood triglyceride levels, and control hormone levels. Prebiotics include any of a number of compositions that are generally not directly digestible by humans, but that are readily digestible by and promote the growth or establishment of probiotic microbes. In one embodiment, a preferred prebiotic comprises a sugar or carbohydrate, e.g., a starch or other carbohydrate-comprising polymer, that can be digested by C. bifermentans and/or C. scindens, but not readily so by other commensals, to thereby favor an increase in the relative proportion or abundance of the administered species. Non-limiting examples of prebiotics include but are not limited to inulin, fructooligosaccharides, galactooligosaccharides, hemicelluloses (e.g., arabinoxylan, xylan, xyloglucan, and glucomannan), chitin, lactulose, mannan oligosaccharides, oligofructose-enriched inulin, gums (e.g., guar gum, gum arabic and carregenaan), oligofructose, oligodextrose, tagatose, resistant maltodextrins (e.g., resistant starch), trans-galactooligosaccharide, pectins (e.g., xylogalactouronan, citrus pectin, apple pectin, and rhamnogalacturonan-I), dietary fibers (e.g., soy fiber, sugarbeet fiber, pea fiber, corn bran, and oat fiber) and xylooligosaccharides, and dietary proteins able to be digested by C. bifermentans and/or C. scindens.

(195) In one embodiment, any of the defined therapeutic microbiota compositions described herein further comprise an effective amount of one or more free Stickland fermentable amino acids, e.g. a preparation of free proline alone or any combination of free amino acids selected from the group consisting of: alanine, leucine, valine, isoleucine, tryptophan, tyrosine, phenylalanine, proline or glycine.

(196) In one embodiment, any of the defined therapeutic microbiota compositions described herein further comprise an effective amount of a polypeptide that can be proteolyzed by the administered species to generate free amino acids fermentable by Stickland fermentation. Inclusion of such a polypeptide provides a ready source of protein for an administered Stickland-fermenting bacterium to digest to amino acids useful for Stickland fermentation by C. difficile. Non-limiting examples of such polypeptides include, but are not limited to casein, gelatin, collagen, and an artificial polymer comprising Stickland acceptor amino acids and/or Stickland donor amino acids. A proline-rich or proline+ leucine-rich protein can also be used. Where an artificial polymer is used, the polymer can comprise Stickland donor amino acids selected from the group consisting of: alanine, leucine, valine, isoleucine, tryptophan, tyrosine and phenylalanine, and/or Stickland acceptor amino acids including proline and/or glycine. The polymer can comprise e.g., a poly[N] amino acid polymer, e.g. a poly[alanine], poly[leucine], etc., or e.g. a copolymer of one or more of the Stickland fermentable amino acids. As a non-limiting example, copolymers can include, e.g. poly[alanine, leucine], poly[alanine, isoleucine],[poly[alanine, tryptophan], etc. Polymers rich in proline would be expected to preferentially promote fermentation via the Stickland proline reductase pathway and repression of C. difficile toxin production.

(197) In one embodiment, any of the compositions described herein, except those which expressly exclude any species other than C. scindens and/or C. bifermentans, further comprise a microbe that supports (e.g., the growth, or viability) C. bifermentans and/or C. scindens. Ruminococcus obeum is an exemplary microbe that has been shown to support C. scindens. Ruminococcus obeum is a genus of bacteria in the class Clostridia found in an abundance in the human gut. A skilled person will be able to determine if a microbe supports C. bifermentans and/or C. scindens, e.g., using complementation assays known in the art.

(198) Establishment of administered C. scindens and/or C. bifermentans as described herein can be evaluated by monitoring the proportion of these species in gut microbiota samples taken over time. An administered species can be considered to be established if that species remains at a level increased relative to its level pre-administration for at least two weeks, preferably at least three weeks, one month, five weeks, six weeks, seven weeks, two months, nine weeks, ten weeks, eleven weeks, three months or more following administration. The presence of the administered species at a relative level of abundance of at least 0.3%, at least 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or more, maintained over time as noted is preferred. Tracking of the administered species can be facilitated by modification of the species to carry a genetic difference or barcode, but this is optional.

(199) Diagnostic Methods

(200) One aspect of the present technology is a method of predicting or determining the likelihood of C. difficile infection or recurrence of C. difficile infection in a subject. Such a prediction can guide prophylactic and subsequent therapeutic treatment decisions. Markers of likely infection or recurrence include, but are not limited to markers in the following classes:

(201) Proteolytic activity of the subject's commensal microbiota, measured, for example, by biochemical assay for proteolysis of a substrate, e.g., one including but not limited to casein or gelatin. Relatively high proteolytic activity is a predictor of reduced likelihood of infection or recurrence.

(202) DNA- or RNA-based studies for commensal proteases and Stickland reductase genes as described herein. The presence and/or expression of commensal protease genes is a predictor of reduced likelihood of infection or recurrence, with higher levels providing benefit.

(203) Microbiologic, biochemical or molecular assays for proteolytic Clostridia, Stickland fermenters, or other highly proteolytic commensal species. The presence of such species is a predictor of reduced likelihood of infection or recurrence, with higher levels providing benefit.

(204) Detection of energy-producing substrates for C. difficile, e.g., substrates selected from proline, Stickland donor amino acids, ethanolamine, glucose, fructose, mannitol, sorbitol, cysteine and threonine. Greater energy-producing substrate levels, and particularly greater levels of substrates preferred by C. difficile are predictors of reduced likelihood of infection or recurrence.

(205) Detection of metabolites of Stickland fermentation including, for example, 5-amino valerate, branched SCFA amino acid metabolites and other Stickland amino acid metabolites. Greater levels of such metabolites are predictive of reduced risk of infection or recurrence. Greater levels of metabolites associated with the proline reductive pathway are particularly predictive.

(206) Detection of metabolites of anaerobic carbohydrate metabolism including, for example the volatile SCFA acetate, propionate or butyrate, and non-volatile SCFA succinate, lactate or pyruvate, where increased levels of volatile SCFA, and of succinate, are predictive of increased likelihood of infection or recurrence.

(207) Detection of microbial energy transporters including NADH/NAD+, NADPH/NADP+, ATP/ADP and GDP/GTP as indicative of the energy state in tested materials from microbial metabolism.

(208) In one embodiment, any or all of the markers noted above can be used with detection of toxigenic C. difficile by microbiologic, toxin ELISA or molecular methods to predict likelihood of infection or recurrence. The presence and/or levels of the various markers can be compared, for example, to a reference to determine likelihood of infection or recurrence. The reference can be, for example, a sample from a healthy individual, or as the case may be a sample from an individual with active C. difficile infection.

(209) In one embodiment, a method is provided for determining the efficacy of therapy for C. difficile. In one embodiment, the therapy is a bacteriotherapy, for example, as described herein. In another embodiment, the therapy is or comprises administration of a pre-biotic, and/or administration of an amino acid or amino acid derivative. In one embodiment, the method comprises measuring in a sample from an individual being treated for C. difficile infection, one or more markers from one or more, two or more, three or more, four or more, or from each of the classes of the markers listed above. In one embodiment, the reference is a sample from an individual with active C. difficile infection. The reference can, but does not necessarily have to be, a sample from the subject being treated, taken before treatment began. A level of activity or expression of one or more markers or classes of markers that is increased relative to the reference indicates effective therapy. In one embodiment, the sample is a stool sample.

(210) In another embodiment, a method is provided for predicting the likelihood of recurrence in a subject being treated or who has been treated for C. difficile infection. In one embodiment, the method comprises measuring in a sample from an individual who has been treated for C. difficile infection, one or more markers from one or more, two or more, three or more, four or more, or from each of the classes of the markers listed above. In one embodiment, the reference is a sample from a healthy individual. A healthy individual is one without active C. difficile infection and who has not received antibiotic treatment within the past three months. A level of one or more biomarkers from one or more of the classes listed above that is below that of the reference indicates an increased risk of recurring C. difficile infection. In one embodiment, the sample is a stool sample. The method can further comprise administering a bacteriotherapy as described herein to an individual for whom the level of such marker(s) is below the reference.

(211) In another embodiment, a method is provided for predicting the risk of an individual for developing a first infection with C. difficile. This is applicable, for example, to those who are elderly, immunocompromised, hospitalized, in a nursing home, receiving antibiotics, or receiving proton pump inhibitors. In one embodiment, the method comprises measuring in a sample from a subject in one or more of these categories one or more markers in one or more of the classes listed above, and the subject is at increased risk of contracting active C. difficile infection if the level of such marker(s) is below a reference. In one embodiment, the reference can be a sample from a healthy individual as above. In another embodiment, the sample from the subject is assayed to determine the presence and/or amount of Stickland fermenting and/or proteolytic bacterial species, including, for example, non-pathogenic Clostridial species that are proteolytic and/or Stickland fermenting. A lack of such species indicates an increased risk for developing active C. difficile infection. A reduced number relative to a healthy reference also indicates increased risk. In one embodiment the method further comprises administering a bacteriotherapy as described herein to an individual for whom such species are lacking or for whom the level of such marker(s) is below the reference.

(212) Further, the markers noted above can be used to define and monitor the efficacious activity of a therapeutic regimen, including, but not limited to a therapeutic regimen comprising administration of bacteriotherapeutic products, e.g., a defined therapeutic microbiota composition or product as described herein.

(213) Also described herein are predictive methods that examine the presence of certain commensal species as a marker of likelihood of C. difficile infection and/or C. difficile toxin production. In one embodiment, such a method comprises: (a) determining the relative abundance of all operational taxonomic units (OTUs) in a sample of the subject's stool that are >90% identical to a reference sequence of C. scindens; (b) determining the relative abundance of all operational taxonomic units (OTUs) in a sample of the subject's stool that are >90% identical to a reference sequence of C. hylemonae; and (c) summing the relative abundances determined in steps (a) and (b), wherein a sum of relative abundances less than or equal to 1% indicates an increased risk of C. difficile recurrence relative to a subject in which the sum of relative abundances is greater than 1%. In one embodiment, relative abundance of the marker species indicative of increased risk is between 1% and 0.01%. As used herein, “relative abundance” refers to comparison with all species of microbes identified in the subject's sample, and is not limited to Clostridium species. The relative abundance of species in a sample can be measured, for example using Roche/454 pyrosequencing or Illumina sequencing for 16S rRNA gene sequencing. This approach, combined with multiplexing produces thousands of 16S rRNA sequences per sample. Microbiome sequencing techniques are further reviewed in, e.g., Grice, E A, and Segre J A. Annu Rev Genomics Hum Genet. 2012; 13:151-170. Relative abundance can additionally be measured using, e.g., using amplicons for microbiologic or microbial products and/or other gene-level targets (e.g., qPCR for genes (e.g., the bai gene, or the gene encoding a Stickland enzyme, a bile acid hydrolase, etc.)).

(214) The predictive method can also be applied to prediction of susceptibility to a first C. difficile infection. Thus, in one embodiment, a sample can be taken from a patient who is at risk of having, has, or has previously had at least one C. difficile infection. A sample can be taken from a subject who has never had a C. difficile infection, but who is in a risk category as noted herein. A stool sample can be collected using standard techniques, e.g., passing stool directly into a clean, dry container.

(215) At least one sample is taken from the subject for the predictive method. However, repeated sampling can also be performed. For example, a sample can be taken from a subject once a day, once a week, twice a month, once a month, or every 3 months following a C. difficile infection to assess the risk of a recurrent C. difficile infection, or a sample can be taken from a subject once a year following a C. difficile infection to assess the risk of a recurrent C. difficile infection. It has even been found that measurement of the relative abundance of the noted species (C. scindens and C. hylemonae) during treatment for an initial C. difficile infection can be predictive of likelihood of a recurrence. Thus, at least one sample can be taken from a subject during a C. difficile infection, e.g., a sample can be taken once a day for the entirety of the infection.

(216) A sample can be taken from a subject who has not previously been treated with antibiotics to treat a C. difficile infection. Alternatively, a sample can be taken from a subject who has been treated with antibiotics to treat a C. difficile infection. The sample can be taken from the subject before, during, or after administration of antibiotics to treat a C. difficile infection. A sample can be taken from a subject before, during, and after administration of an antibiotic (e.g., a sample is taken from a subject during and after administration of an antibiotic).

(217) The method can further comprise the step of administering a further therapeutic or prophylactic treatment, including, for example, an FMT or any of the bacterial compositions described herein to a subject when the sum of relative abundances relative level is at or below 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1.0%.

(218) In this context, the reference sequence of C. scindens can be a sequence comprising at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the sequence of SEQ ID NO: 31. Similarly, in this context, the reference sequence of C. hylemonae can be a sequence comprising at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the sequence of SEQ ID NO: 32.

(219) In another aspect of any of the embodiments, described herein is a method of treating a pathology involving expression of a bacterial toxin from a Gram positive, spore-forming species in a subject in need thereof, the method comprising: a) determining that the subject has a reduced amount and/or activity of secreted proteolytic enzymes in a gut or stool sample relative to healthy individual as described herein; and b) administering a therapeutic bacterial species as described herein to the subject. In some embodiments of any of the aspects, the step of determining that the subject has a reduced amount and/or activity of a secreted proteolytic enzyme can comprise i) obtaining or having obtained a biological sample from the subject and ii) performing or having performed an assay on the sample obtained from the subject to determine/measure the level of the proteolytic enzyme in the subject. Methods to measure amount of secreted proteolytic enzymes and/or activity are known to a skilled artisan. Such methods to measure gene expression products, e.g., protein level, include ELISA (enzyme linked immunosorbent assay), western blot, immunoprecipitation, and immunofluorescence using detection reagents such as an antibody or protein binding agents. Alternatively, a peptide can be detected in a subject by introducing into a subject a labeled anti-peptide antibody. For example, the antibody can be labeled with a detectable marker whose presence and location in the subject is detected by standard imaging techniques. Methods to measure the activity of secreted proteolytic enzymes are known to a skilled artisan. For example, a protease activity assay that uses casein or gelatin as a substrate can be used to measure the activity of a protease in a biological sample (Cat. No. Ab111750; Abcam, Cambridge Mass.).

(220) In another aspect, described herein is a method of treating a pathology involving expression of a bacterial toxin brom a Gram positive spore-forming bacterium in a subject in need thereof, the method comprising: a) determining that a sample from the subject has a decreased amount and/or activity of proline reductase relative to a sample from a healthy individual; and b) administering a therapeutic bacterial species as described herein to the subject. In one embodiment, the step of determining that a sample from the subject has reduced level or activity of proline reductase can comprise i) obtaining or having obtained a biological sample from the subject and ii) performing or having performed an assay on the sample obtained from the subject to determine/measure the level of the proline reductase in the subject. Methods to measure amount or activity of proline reductase are known to a skilled artisan and/or described herein. Such methods can include measurement of gene expression products, e.g., protein level, and include for example, ELISA (enzyme linked immunosorbent assay), western blot, immunoprecipitation, and immunofluorescence using detection reagents such as an antibody or protein binding agents.

(221) In another aspect of any of the embodiments, described herein is a method of treating a pathology involving expression of a bacterial toxin brom a Gram positive spore-forming bacterium in a subject in need thereof, the method comprising: a) determining that a sample from the subject has a decreased amount and/or activity of glycine reductase relative to a sample from a healthy individual; and b) administering a therapeutic bacterial species as described herein to the subject. In one embodiment, the step of determining that a sample from the subject has reduced level or activity of glycine reductase can comprise i) obtaining or having obtained a biological sample from the subject and ii) performing or having performed an assay on the sample obtained from the subject to determine/measure the level of the glycine reductase in the subject. Methods to measure amount or activity of glycine reductase are known to a skilled artisan and/or described herein. Such methods can include measurement of gene expression products, e.g., protein level, and include for example, ELISA (enzyme linked immunosorbent assay), western blot, immunoprecipitation, and immunofluorescence using detection reagents such as an antibody or protein binding agents.

(222) Dosage, Administration and Formulations

(223) In one aspect, any of the compositions described herein is administered to a subject that has, or has been diagnosed with C. difficile infection. In one embodiment, the C. difficile infection is a recurrent C. difficile infection. Recurrent C. difficile infections can be caused by the same or a different C. difficile strain that caused a previous C. difficile infection. In one embodiment, the subject is at risk for a C. difficile infection or a recurrent C. difficile infection.

(224) A clinician can diagnose a subject as having a C. difficile infection using standard methods to detect toxins that are produced by C. difficile bacteria. For example, a stool sample from subject suspected of having a C. difficile infection can be analyzed via an enzyme immunoassay or even dipstick/lateral flow immunoassay for the C. difficile toxin(s), PCR-based assays, GDH/EIA tests, or cell cytotoxicity assays are also commonly used to definitively determine C. difficile infection. Imaging, e.g., colonoscopy or abdominal x-ray or CT scan can also be used to assist the diagnosis of C. difficile infection.

(225) A clinician can determine is a subject is at risk of having a C. difficile infection by assessing a subject's risk factors, including but not limited to the subject's proximity to an individual who has or has recently had a C. difficile infection, current medications that promote C. difficile growth in the intestine, age, antibiotic use (length of antibiotic regimen, use of broad-spectrum antibiotics, or use of multiple antibiotics, use of gastric acid inhibitors such as proton pump-inhibitors and or histamine-2 receptor antagonists. At present, a subject who has had previous C. difficile infection is at risk of a recurrent C. difficile infection; approximately 20% of subjects who have had a C. difficile infection will have a recurrent C. difficile infection. In a further embodiment, risk of recurrence can be evaluated with the method described herein above that measures the relative abundance of C. scindens and C. hylemonae. Risk of recurrence can also be predicted via one or more of the diagnostic methods described herein.

(226) Dosage

(227) The dosage ranges for the bacterial species described herein in a defined therapeutic microbiota composition depends upon the potency (including viability), and includes amounts large enough to produce the desired effect, e.g., reduction in at least one symptom of a C. difficile infection in a treated subject. The dosage should not be so large as to cause unacceptable adverse side effects. Generally, the dosage can vary with the type of illness, e.g., first infection vs. recurrent infection, and with the age, condition, and sex of the patient. The dosage can be determined by one of skill in the art and can also be adjusted by the individual physician in the event of any complication.

(228) For use in the various aspects described herein, an effective amount of cells in a composition as described herein comprises at least 1×10.sup.5 bacterial cells, at least 1×10.sup.6 bacterial cells, at least 1×10.sup.7 bacterial cells, at least 1×10.sup.8 bacterial cells, at least 1×10.sup.9 bacterial cells, at least 1×10.sup.10 bacterial cells, at least 1×10.sup.11 bacterial cells, at least 1×10.sup.12 bacterial cells or more. In one embodiment, the microbial consortium or the individual bacterial components thereof can be obtained from a microbe bank. Members of a therapeutic or preventive/prophylactic consortium are generally administered together, e.g., in a single admixture. However, it is specifically contemplated herein that members of a given consortium can be administered as separate dosage forms or sub-mixtures or sub-combinations of the consortium members (e.g., C. scindens and C. bifermentans can be comprised in two separate compositions that are administered as separate doses). Thus, a consortium of e.g., C. scindens and C. bifermentans, can be administered, for example, as a single preparation including all members (in one or more dosage units, e.g., one or more capsules) or as two separate preparations that, in sum, include all members of the given consortium. While administration as a single admixture is preferred, a potential advantage of the use of e.g., individual units for each member of a consortium, is that the species administered to any given subject can be tailored, if necessary, by selecting the appropriate combination of, for example, single species dosage units that together comprise the desired consortium. With respect to the administration of two separate preparations, the route of administration can be the same for each preparation (e.g., the first and second preparation can be administered orally), or different for each preparation (e.g., the first preparation can be administered orally and the second preparation is administered directly to the colon via colonoscope, to the small intestine via endoscope, or to the colon via suppository or enema).

(229) From the conventional mouse model (administer microbes after onset of symptomatic Cdiff infection) it was found that orally administered C. bifermentans rapidly changes the cecal environment 6-7 hr after administration (transit time through the gut). This does not occur with C. sardiniense. It is noted that C. bifermentans persistence in most conventional mice is only a few days but is sufficient to correct the gut environment and cause Cdiff to rapidly halt toxin production. The administered bacteriotherapy can, for example, provide long-term engraftment, e.g., weeks, months or longer, or, it can provide shorter term persistence or presence of the administered species. Where long-term engraftment does not occur, repeat dosing is warranted, for example to provide continuing protection for as long as needed, including days, weeks, months, years or longer, e.g., indefinitely if needed. The need for such continued dosing can be evaluated, e.g., using methods of evaluating risk of infection or recurrent infection as described herein.

(230) One can also easily adjust the ratio of one species to another if separate dosage forms are administered. It is contemplated that the ratios of C. scindens to C. bifermentans, for example, can be varied, e.g. over a range of 1:10 to 10:1 with benefit to the patient under certain circumstances, especially where, for example, the persistence of one species is found to be less than that of the other. Such a finding would warrant, for example, increasing the ratio in favor of the species with the lower degree of persistence. In one embodiment, the ratio of C. scindens to C. bifermentans in a composition described herein is 1:1. The ratio of C. scindens to C. bifermentans in a composition described herein can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10. The ratio of C. bifermentans to C. scindens in a composition described herein can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10. The ratio should be such that the amount of each bacteria in the composition is sufficient to promote engraftment (i.e., in vivo replication) of each species in a subject's GI tract following administration of the composition.

(231) A pharmaceutical composition comprising a microbial consortium can be administered by any method suitable for depositing in the gastrointestinal tract, preferably the colon, of a subject (e.g., human, mammal, animal, etc.). Examples of routes of administration include rectal administration by colonoscopy, suppository, enema, upper endoscopy, or upper push enteroscopy. Additionally, intubation through the nose or the mouth by nasogastric tube, nasoenteric tube, or nasal jejunal tube can be utilized. Oral administration by a solid such as a pill, tablet, a suspension, a gel, a geltab, a semisolid, a tablet, a sachet, a lozenge or a capsule or microcapsule, or as an enteral formulation, or re-formulated for final delivery as a liquid, a suspension, a gel, a geltab, a semisolid, a tablet, a sachet, a lozenge or a capsule, or as an enteral formulation can be utilized as well. Also contemplated herein are food items that are inoculated with a microbial consortium as described herein.

(232) In some embodiments, the compositions described herein can be administered in a form containing one or more pharmaceutically acceptable carriers. Suitable carriers are well known in the art and vary with the desired form and mode of administration of the composition. For example, pharmaceutically acceptable carriers can include diluents or excipients such as fillers, binders, wetting agents, disintegrators, surface-active agents, glidants, lubricants, and the like. The carrier may be a solid (including powder), liquid, or combinations thereof. Each carrier is preferably “acceptable” in the sense of being compatible with the other ingredients in the composition and not injurious to the subject. The carrier may be biologically acceptable and inert (e.g., it permits the composition to maintain viability of the biological material until delivered to the appropriate site).

(233) Oral compositions can include an inert diluent or an edible carrier. For the purpose of oral therapeutic administration, the active compound can be incorporated with excipients and used in the form of tablets, lozenges, pastilles, troches, or capsules, e.g., gelatin capsules. Oral compositions can also be prepared by combining a composition of the present disclosure with a food. In one embodiment a food used for administration is chilled, for instance, iced flavored water. Pharmaceutically compatible binding agents, and/or adjuvant materials can be included as part of the composition. The tablets, pills, capsules, troches and the like can contain any of the following ingredients, or compounds of a similar nature: a binder such as microcrystalline cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent such as alginic acid, primogel, or corn starch; a lubricant such as magnesium stearate or sterotes; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; or a flavoring agent such as peppermint, methyl salicylate, orange flavoring, or other suitable flavorings. These are for purposes of example only and are not intended to be limiting.

(234) The compositions comprising a microbial consortium can also be prepared in the form of suppositories (e.g., with conventional suppository bases such as cocoa butter and other glycerides) or retention enemas for rectal delivery. Suppositories can comprise one a number of species in a microbial consortium (e.g., a suppository can comprise a C. scindens and a C. bifermentans, or a suppository can comprise a C. scindens or a C. bifermentans). Suppositories comprising only one species of the microbial consortium can be co-administered with another composition comprising another species of the consortium, such that co-administration will equal the sum of the given consortium. The compositions can be prepared with carriers that will protect the consortium against rapid elimination from the body, such as a controlled release formulation, including implants. Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Such formulations can be prepared using standard techniques. The materials can also be obtained commercially from, for instance, Alza Corporation and Nova Pharmaceuticals, Inc. Liposomal suspensions can also be used as pharmaceutically acceptable carriers. These can be prepared according to methods known to those skilled in the art.

(235) In some embodiments, a composition can be encapsulated, e.g., enteric-coated formulations). For instance, when the composition is to be administered orally, the dosage form is formulated so the composition is not exposed to conditions prevalent in the gastrointestinal tract before the small intestine, e.g., high acidity and digestive enzymes present in the stomach. The encapsulation of compositions for therapeutic use is routine in the art. Encapsulation can include hard-shelled capsules, which can be used for dry, powdered ingredients soft-shelled capsules. Capsules can be made from aqueous solutions of gelling agents such as animal protein (e.g., gelatin), plant polysaccharides or derivatives like carrageenans and modified forms of starch and cellulose. Other ingredients can be added to a gelling agent solution such as plasticizers (e.g., glycerin and or sorbitol), coloring agents, preservatives, disintegrants, lubricants and surface treatment.

(236) In one embodiment, a microbial consortium as described herein is formulated with an enteric coating. An enteric coating can control the location of where a microbial consortium is released in the digestive system. Thus, an enteric coating can be used such that a microbial consortium-containing composition does not dissolve and release the microbes in the stomach, which can be a toxic environment for many microbes, but rather travels to the small intestine, where it dissolves and releases the microbes in an environment where they can survive. An enteric coating can be stable at low pH (such as in the stomach) and can dissolve at higher pH (for example, in the small intestine). Material that can be used in enteric coatings includes, for example, alginic acid, cellulose acetate phthalate, plastics, waxes, shellac, and fatty acids (e.g., stearic acid, palmitic acid). Enteric coatings are described, for example, in U.S. Pat. Nos. 5,225,202, 5,733,575, 6,139,875, 6,420,473, 6,455,052, and 6,569,457, all of which are herein incorporated by reference in their entirety. The enteric coating can be an aqueous enteric coating. Examples of polymers that can be used in enteric coatings include, for example, shellac (trade name EmCoat 120 N, Marcoat 125); cellulose acetate phthalate (trade names AQUACOAT™, AQUACOAT ECD™, SEPIFILM™, KLUCEL™, and METOLOSE™); polyvinylacetate phthalate (trade name SURETERIC™); and methacrylic acid (trade name EUDRAGIT™).

(237) In one embodiment, an enteric coated prebiotic composition that additionally comprises members of a microbial consortium as described herein is administered to a subject. In another embodiment, an enteric coated probiotic and prebiotic composition is administered to a subject.

(238) Formulations suitable for rectal administration include gels, aqueous or oily suspensions, dispersible powders or granules, emulsions, dissolvable solid materials, enemas, and the like. The formulations are preferably provided as unit-dose suppositories comprising the active ingredient in one or more solid carriers forming the suppository base, for example, cocoa butter. Suitable carriers for such formulations include petroleum jelly, lanolin, polyethyleneglycols, alcohols, and combinations thereof, provided they are compatible with the bacterial species preparation being administered.

(239) In some embodiments, the microbial consortium can be formulated in a food item. Some non-limiting examples of food items to be used with the methods and compositions described herein include: popsicles, cheeses, creams, chocolates, milk, meat, drinks, yogurt, pickled vegetables, kefir, miso, sauerkraut, etc. In other embodiments, the food items can be juices, refreshing beverages, tea beverages, drink preparations, jelly beverages, and functional beverages; alcoholic beverages such as beers; carbohydrate-containing foods such as rice food products, noodles, breads, and pastas; paste products such as fish, hams, sausages, paste products of seafood; retort pouch products such as curries, food dressed with a thick starchy sauce, and Chinese soups; soups; dairy products such as milk, dairy beverages, ice creams, cheeses, and yogurts; fermented products such as fermented soybean pastes, fermented beverages, and pickles; bean products; various confectionery products including biscuits, cookies, and the like, candies, chewing gums, gummies, cold desserts including jellies, cream caramels, and frozen desserts; instant foods such as instant soups and instant soy-bean soups; and the like. It is preferred that food preparations not require cooking after admixture with the microbial consortium to avoid killing the microbes.

(240) Formulations of a microbial consortium can be prepared by any suitable method, typically by uniformly and intimately admixing the consortium with liquids or finely divided solid carriers or both, in the required proportions and then, if necessary, shaping the resulting in mixture into the desired shape. In addition, the microbial consortium can be treated to prolong shelf-life, preferably the shelf-life of the pre-determined gut flora will be extended via freeze drying.

(241) In some embodiments, the microbial consortium as described herein is combined with one or more additional probiotic organisms prior to treatment of a subject.

(242) A nutrient supplement comprising the microbial consortium as described herein can include any of a variety of nutritional agents, including vitamins, minerals, essential and nonessential amino acids, carbohydrates, lipids, foodstuffs, dietary supplements, short chain fatty acids and the like. Preferred compositions comprise vitamins and/or minerals in any combination. Vitamins for use in a composition as described herein can include vitamins B, C, D, E, folic acid, K, niacin, and like vitamins. The composition can contain any or a variety of vitamins as may be deemed useful for a particularly application, and therefore, the vitamin content is not to be construed as limiting. Typical vitamins are those, for example, recommended for daily consumption and in the recommended daily amount (RDA), although precise amounts can vary. The composition can preferably include a complex of the RDA vitamins, minerals and trace minerals as well as those nutrients that have no established RDA, but have a beneficial role in healthy human or mammal physiology. The amount of material included in the composition can vary widely depending upon the material and the intended purpose for its absorption, such that the composition is not to be considered as limiting.

(243) Also contemplated herein are kits comprising, at a minimum, a biotherapeutic microbial species or a consortium prep or formulations comprising the members of the consortium, e.g., C. scindens and C. bifermentans species, in an admixture or comprising the members of the consortium in sub-combinations or sub-mixtures. In some embodiments, the kit further comprises empty capsules to be filled by the practitioner and/or one or more reagents for enteric coating such capsules. It is also contemplated herein that the microbe preparation is provided in a dried, lyophilized or powdered form. In one embodiment, the kit comprises a strain of C. bifermentans. In another embodiment, the kit comprises a strain of C. scindens and a strain of C. bifermentans. The C. scindens strain comprised in the kit can be a C. scindens strain comprising a 16S rRNA sequence that is at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO: 1. The C. bifermentans strain comprised in the kit can be a C. bifermentans strain comprising a 16S rRNA sequence that is at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO: 2. In another embodiment, the kit comprises at least one reducing agent such as N-acetylcysteine, cysteine, or methylene blue for growing, maintaining and/or encapsulating the microbes under anaerobic conditions. The kits described herein are also contemplated to include cell growth media and supplements necessary for expanding the microbial preparation. The kits described herein are also contemplated to include one or more prebiotics as described herein.

(244) Prior to administration of the bacterial composition, the patient may optionally have a pretreatment protocol to prepare the gastrointestinal tract to receive the bacterial composition. In these instances, the pretreatment protocol can enhance the ability of the bacterial composition to affect the patient's microbiota balance. In an alternative embodiment, the subject is not pre-treated with an antibiotic.

(245) Generally, the defined therapeutic microbiota described herein can be administered after the completion of a course of antibiotics for the treatment of C. difficile infection. However, use of the defined therapeutic microbiota alone to prevent or, for that matter, directly combat the C. difficile infection is specifically contemplated. If a patient has received antibiotics for treatment of an infection other than C. difficile or for C. difficile, in one embodiment the antibiotic should be stopped in sufficient time to allow the antibiotic to be substantially reduced in concentration in the gut before the bacterial composition is administered. In one embodiment, the antibiotic may be discontinued 1, 2, or 3 days before the administration of the bacterial composition. In one embodiment, the antibiotic can be discontinued 3, 4, 5, 6, or 7 antibiotic half-lives before administration of the bacterial composition.

(246) In another embodiment, the bacterial compositions described herein are administered before or concurrently with an antibiotic. In one embodiment, administration of therapeutic microbiota before or concurrently with antibiotic might be contemplated where the administered species are at least somewhat resistant to the effects of the antibiotic administered. In another embodiment, an antibiotic is administered before the administration to the bacterial composition (e.g., less than 1 day, 1, 2, 3, 4, 5, 6, or 7 days before administration of the bacterial composition). Longer times can help to prevent the antibiotic from killing the administered bacteriotherapeutic organism(s). In one embodiment, the antibiotic administered is an antibiotic used to treat C. difficile infection (e.g., metronidazole (Flagyl), vancomycin (Vancocin), or fidaxomicin (Dificid)). In another embodiment, the antibiotic is not specific to treatment of a C. difficile infection, but is an antibiotic known in the art to have therapeutic effects on the intestinal system (e.g., norfloxacin, cephalexin, trimethoprim-sulfamethoxazole, or levofloxacin). Antibiotics listed herein are for purposes of example only and are not intended to be limiting.

(247) In one embodiment, the bacterial compositions described herein are administered with an antacid or proton pump inhibitor (PPI). An antacid works to neutralize the stomach acid, which can interfere to efficient delivery of the bacterial compositions described herein. An antacid can be administered prior to, in combination with, or after the administration of the bacterial compositions described herein. In one embodiment, the bacterial composition can be formulation in a composition that further comprises an antacid. Antacids are known in the art and can comprise the following active ingredients: calcium carbonate, aluminum, magnesium, sodium bicarbonate, and/or alginic acid. Proton pump inhibitors block activity of the H+/K+ ATPase proton pump in stomach epithelium.

(248) Any of the preparations described herein can be administered once on a single occasion or on multiple occasions, such as once a day for several days or more than once a day on the day of administration (including twice daily, three times daily, or up to five times daily). Or the preparation can be administered intermittently according to a set schedule, e.g., once weekly, once monthly, or when the patient relapses from the primary illness. In another embodiment, the preparation can be administered on a long-term basis to assure the maintenance of a protective or therapeutic effect.

(249) Efficacy

(250) Typically, a C. difficile infection can manifest with one of more of the following clinical symptoms or indicators: (i) mild (at least 3 times a day) to severe (4 or more times a day) watery diarrhea, (ii) abdominal pain, (iii) blood and/or pus in the stool, (iv) fever, and (v) loss of appetite. Quantitatively, a C. difficile infection can be assessed by quantitative factors (i) detectable levels of C. difficile toxin, and (ii) detectable levels of C. difficile bacteria. Thus, efficacious treatment and/or prevention of a C. difficile infection using the methods and compositions described herein can reduce or eliminate at least one of the symptoms or indicators associated with a C. difficile infection, as described above. Methods for the measurement of each of these parameters (e.g., measuring the levels of C. difficile toxins) are known to those of ordinary skill in the art and/or described herein.

(251) Effective treatment can be determined by an overall decrease in the Bristol Score from 7 or 6 to a lower value. Alternatively, or in addition, effective treatment can be determined by a decrease, as the term is used herein, in C. difficile biomass or relative abundance in the stool, or by a decrease in C. difficile toxin in the stool.

(252) Efficacy can also be measured by failure of a subject to worsen as assessed by need for medical interventions (e.g., progression of infection is halted or at least slowed). Methods of measuring these indicators are known to those of skill in the art and/or described herein. Example methods include PCR-based or Enzyme-linked immunosorbent assay (ELISA) to detect C. difficile toxin. Treatment includes: (1) inhibiting the infection, e.g., arresting, or slowing symptoms of the infection, for example watery diarrhea; or (2) relieving the infection, e.g., causing regression of symptoms, reducing the symptoms by at least 10%, and/or reducing C. difficile toxin levels by at least 10% compared to a reference level (e.g., a C. difficile toxin level prior to administration; and (4) restoring healthy intestinal flora, thus preventing future C. difficile infection or production. It is expected that the levels of C. difficile toxin and/or C. difficile bacteria present in a subject's intestine should be reduced to levels seen in healthy individuals or below detectable levels at least 1 week, at least 2 weeks, at least 3, weeks, at least 4 weeks following administration of any of the therapeutic compositions described herein.

(253) Therapeutic microbiota, including defined therapeutic microbiota as described herein, are administered in an amount sufficient, or an amount effective, to provide therapeutic benefit. An effective amount of a composition for the treatment of C. difficile infection means that amount which, when administered to a mammal in need thereof, is sufficient to result in effective treatment as that term is defined herein, for that infection. Efficacy of the composition can be determined by a physician by assessing physical indicators of C. difficile infection as described above.

(254) The term “effective amount” as used herein refers to the amount of a therapeutic microbiota composition as described herein needed to alleviate at least one or more symptoms or reduces one or more indicator of a C. difficile infection, and relates to a sufficient amount of pharmacological composition to provide the desired effect. The term “therapeutically effective amount” therefore refers to an amount of a composition that is sufficient to provide a particular effect when administered to a typical subject. An effective amount as used herein, in various contexts, would also include an amount sufficient to delay the development of a symptom of the infection, alter the course of a symptom (for example but not limited to, slowing the progression of a symptom of the infection), or reverse a symptom of the infection. Thus, it is not generally practicable to specify an exact “effective amount.” However, for any given case, an appropriate “effective amount” can be determined by one of ordinary skill in the art using only routine experimentation. The term “effective amount” is used interchangeably with the term “therapeutically effective amount” and refers to the amount of at least one agent, e.g., a bacterial composition that treats a C. difficile infection, at dosages and for periods of time necessary to achieve the desired therapeutic result, for example, to reduce or stop at least one symptom or indicator of such C. difficile infection, in the subject.

(255) Repeated administration of the defined therapeutic microbiota composition may be beneficial to maintain a protective or curative effect.

(256) Effective amounts, toxicity, and therapeutic efficacy of drug agents, e.g., for formulations or treatments using antibiotics in addition to microbes, can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD.sub.50 (the dose lethal to 50% of the population) and the ED.sub.50 (the dose therapeutically effective in 50% of the population). The dosage can vary depending upon the dosage form employed and the route of administration utilized. The dose ratio between toxic and therapeutic effects is the therapeutic index and can be expressed as the ratio LD.sub.50/ED.sub.50. Compositions and methods that exhibit large therapeutic indices are preferred. A therapeutically effective dose can be estimated initially from in vivo assays. It is contemplated that the relevant level for an agent that treat a C. difficile infection may also be the level achieved in the lumen of the gut. The effects of any particular dosage can be monitored by a suitable bioassay or by measurement of administered and stable biomass (engraftment, persistence) and microbial metabolic activities (Stickland metabolite production, free amino acids, protease activities, associate gene content or expression levels)

(257) The dosage can be determined by a physician and adjusted, as necessary, to suit observed effects of the treatment.

(258) All patents and other publications; including literature references, issued patents, published patent applications, and co-pending patent applications; cited throughout this application are expressly incorporated herein by reference for the purpose of describing and disclosing, for example, the methodologies described in such publications that might be used in connection with the technology described herein. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents.

(259) The description of embodiments of the disclosure is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. While specific embodiments of, and examples for, the disclosure are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the disclosure, as those skilled in the relevant art will recognize. For example, while method steps or functions are presented in a given order, alternative embodiments may perform functions in a different order, or functions may be performed substantially concurrently. The teachings of the disclosure provided herein can be applied to other procedures or methods as appropriate. The various embodiments described herein can be combined to provide further embodiments. Aspects of the disclosure can be modified, if necessary, to employ the compositions, functions and concepts of the above references and application to provide yet further embodiments of the disclosure. Moreover, due to biological functional equivalency considerations, some changes can be made in protein structure without affecting the biological or chemical action in kind or amount. These and other changes can be made to the disclosure in light of the detailed description. All such modifications are intended to be included within the scope of the appended claims.

(260) Specific elements of any of the foregoing embodiments can be combined or substituted for elements in other embodiments. Furthermore, while advantages associated with certain embodiments of the disclosure have been described in the context of these embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the disclosure.

(261) The technology described herein is further illustrated by the following examples which in no way should be construed as being further limiting.

(262) Some embodiments of the technology described herein can be defined according to any of the following numbered paragraphs:

(263) 1. A pharmaceutical composition comprising an oral formulation comprising C. scindens and C. bifermentans bacteria.

(264) 2. A composition comprising C. scindens and C. bifermentans bacteria, wherein one or both of the C. scindens and C. bifermentans bacteria is in dried, viable form.

(265) 3. A pharmaceutical composition comprising a formulation comprising C. scindens and C. bifermentans bacteria, wherein the composition does not comprise Bacteroides species or Escherichia species.

(266) 4. The composition of any one of paragraphs 1-3, wherein one or both of the C. scindens and C. bifermentans bacteria are in spore form.

(267) 5. The composition of any one of paragraphs 1-3, wherein one or both of the C. scindens and C. bifermentans bacteria are not in spore form.

(268) 6. The composition of any one of paragraphs 1-3, wherein the C. scindens and C. bifermentans bacteria are present as a mixture of metabolically active and spore forms.

(269) 7. The composition of any one of paragraphs 1-3, wherein the composition comprises a capsule or microcapsule, or a composition formulated for enteric delivery.

(270) 8. The composition of paragraph 1 or paragraph 3, wherein one or both of the C. scindens and C. bifermentans bacteria are in dried viable form.

(271) 9. The composition of any one of paragraphs 1-3, which does not comprise C. sardiniensis bacteria.

(272) 10. The composition of any one of paragraphs 1-3, which does not comprise any other Clostridium species.

(273) 11. The composition of either of paragraphs 1 or 2, which does not contain Bacteroides species or Escherichia coli.

(274) 12. The composition of any one of paragraphs 1-3, in which the formulation comprises no other bacteria.

(275) 13. A pharmaceutical composition comprising an oral formulation comprising a first bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. scindens bacterium, and a second bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium.
14. A composition comprising a first bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. scindens bacterium, and a second bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium, wherein one or both of the C. scindens and C. bifermentans bacteria is in dried, viable form.
15. A pharmaceutical composition comprising a formulation comprising a first bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. scindens bacterium, and a second bacterial population that has 16S rDNA with a sequence at least 97% identical to a 16S rDNA sequence present in a reference C. bifermentans bacterium wherein the composition does not comprise Bacteroides species or Escherichia species.
16. The composition of any one of paragraphs 13-15, wherein one or both of the C. scindens and C. bifermentans bacteria are in spore form.
17. The composition of any one of paragraphs 13-15, wherein one or both of the C. scindens and C. bifermentans bacteria are not in spore form.
18. The composition of any one of paragraphs 13-15, wherein the C. scindens and C. bifermentans bacteria are present as a mixture of metabolically active and spore forms.
19. The composition of any one of paragraphs 13-15, wherein the composition comprises a capsule or microcapsule, or a composition formulated for enteric delivery.
20. The composition of paragraph 13 or paragraph 15, wherein one or both of the C. scindens and C. bifermentans bacteria are in dried viable form.
21. The composition of any one of paragraphs 13-15, which does not comprise C. sardiniense bacteria
22. The composition of either of paragraphs 13 or 14, which does not comprise Bacteroides species or Escherichia coli.
23. The composition of any one of paragraphs 13-15, which does not comprise any other Clostridium species.
24. The composition of any one of paragraphs 13-15, in which the formulation comprises no other bacteria.
25. The composition of any one of paragraphs 1-24, further comprising a prebiotic.
26. The composition of any one of paragraphs 1-11, 23, or 25, further comprising a microbe that supports C. scindens and/or C. bifermentans.
27. The composition of paragraph 26, wherein the microbe that supports C. scindens is Ruminococcus obeum.
28. The composition of any one of paragraphs 1-27, for use in the treatment of C. difficile infection.
29. The composition for use of paragraph 28, wherein the use comprises suppressing the expression of C. difficile toxin.
30. The composition for use of paragraph 28, wherein the use comprises promoting a shift towards use of the proline reductase pathway of Stickland fermentation in C. difficile.
31. The composition for use of paragraph 28, wherein the use comprises inducing CodY activity or expression in C. difficile.
32. The composition for use of paragraph 28, wherein the use comprises promoting ethanolamine utilization by C. difficile.
33. A method comprising administering a composition of any one of paragraphs 1-27 to a subject in need thereof.
34. The method of paragraph 33, wherein the subject has or has been diagnosed with C. difficile infection.
35. The method of paragraph 34, wherein the C. difficile infection is recurrent.
36. The method of paragraph 33, wherein the subject is at risk of C. difficile infection or recurrent C. difficile infection.
37. The method of paragraph 33, wherein the administration is oral.
38. A method comprising administering a composition of any one of paragraphs 2, 3, 14 or 15 directly to the colon of a subject in need thereof.
39. The method of paragraph 38, wherein administration is via colonoscope or enema.
40. The method of any of paragraphs 33-39, wherein the subject is receiving or has recently received antibiotic treatment.
41. A method of treating an infection, the method comprising administering an antibiotic and a composition of any one of paragraphs 1-27.
42. The method of paragraph 41, wherein the composition is administered before or concurrently with the antibiotic.
43. The method of paragraph 41, wherein the composition is administered after a course of an antibiotic.
44. A method of predicting recurrence of C. difficile infection in a subject, the method comprising: (a) determining the relative abundance of all operational taxonomic units (OTUs) in a sample of the subject's stool that are >90% identical to a reference sequence of C. scindens; (b) determining the relative abundance of all operational taxonomic units (OTUs) in a sample of the subject's stool that are >90% identical to a reference sequence of C. hylemonae; and (c) summing the relative abundances determined in steps (a) and (b), wherein a sum of relative abundances less than or equal to 1% indicates an increased risk of C. difficile recurrence relative to a subject in which the sum of relative abundances is greater than 1%.
45. The method of paragraph 44, wherein the reference sequences for C. scindens and C. hylemonae are 16S rDNA sequences.
46. The method of paragraph 44 or 45, wherein the determining steps are performed on samples taken before, during or after the subject has been treated with antibiotics for C. difficile infection.
47. The method of paragraph 44 or 45, wherein the determining steps are performed on samples taken after the subject has been treated with antibiotics for C. difficile infection
48. The method of paragraph 44, further comprising the step, when the sum of relative abundances is at or below 1%, of administering a composition of any one of paragraphs 1-27.
49. A method of suppressing expression of a bacterial toxin in a subject, the method comprising administering a defined bacterial microbiota comprising at least one bacterial organism that encodes and secretes a protease and/or performs Stickland fermentation.
50. A method of treating or preventing a pathology caused by expression of a bacterial toxin, the method comprising administering a defined bacterial microbiota comprising at least one bacterial organism that encodes and secretes a protease and/or performs Stickland fermentation.
51. A method of promoting CodY expression or activity in a C. difficile bacterium in a subject, the method comprising administering a defined bacterial microbiota comprising a bacterial organism that encodes and secretes a protease and/or performs Stickland fermentation.
52. A method of promoting ethanolamine utilization by a C. difficile bacterium in a subject, the method comprising administering a defined bacterial microbiota comprising a bacterial organism that encodes and secretes a protease and/or performs Stickland fermentation.
53. The method of any one of paragraphs 49-52, wherein at least one bacterial organism encodes and secretes at least one protease selected from the group consisting of: a protease of PATRIC ID fig|186802.30.peg.279; a protease of PATRIC ID fig|186802.30.peg.290; a protease of PATRIC ID fig|186802.30.peg.313; a protease of PATRIC ID fig|186802.30.peg.414; a protease of PATRIC ID fig|186802.30.peg.543; a protease of PATRIC ID fig|186802.30.peg.2205; a protease of PATRIC ID fig|186802.30.peg.2313; a protease of PATRIC ID fig|186802.30.peg.2680; a protease of PATRIC ID fig|186802.30.peg.2745; a protease of PATRIC ID fig|186802.30.peg.2746; a protease of PATRIC ID fig|186802.30.peg.830; a protease of PATRIC ID fig|186802.30.peg.921; a protease of PATRIC ID fig|186802.30.peg.936; a protease of PATRIC ID fig|186802.30.peg.3000; a protease of PATRIC ID fig|186802.30.peg.3018; a protease of PATRIC ID fig|186802.30.peg.3019; and a protease of PATRIC ID fig|186802.30.peg.3065.
54. The method of any of paragraphs 49-52, wherein at least one protease performs the proteolysis reaction of enzymes of Enzyme Commission number (E.C. number) EC 3.4.21.-; EC 3.4.21.53; or EC 3.4.21.92.
55. The method of any of paragraphs 49-52, wherein at least one bacterial organism encodes and expresses one or more of D-proline reductase, Glycine reductase, Thioredoxin, or Choloylglycine hydrolase.
56. The method of any of paragraphs 49-52, wherein the at least one bacterial organism falls within Clostridial cluster I, XI, or XIVa, and does not express a pathology-causing bacterial toxin.
57. The method of paragraph 56, wherein the bacterial organism in Clostridial cluster I is selected from C. sporogenes, and C. histolyticum.
58. The method of paragraph 56, wherein the bacterial organism in Clostridial cluster XI is selected from C. bifermentans, C. hiranonis, and P. anaerobius.
59. The method of paragraph 56, wherein the bacterial organism in Clostridial cluster XIVa is selected from C. scindens, C. clostriiforme, and C. nexile.
60. The method of any of paragraphs 49-52, wherein the at least one bacterial organism inhibits sorbitol/mannitol fermentation by C. difficile.
61. The method of any of paragraphs 49-52, wherein the at least one bacterial organism promotes Stickland fermentation through the acceptor amino acid proline, or activation of proline reductase.
62. The method of any of paragraphs 49-52, wherein the at least one bacterial organism promotes 5-aminovalerate production.
63. The method of any of paragraphs 49-52, wherein the bacterial toxin is a C. difficile toxin.
64. The method of any of paragraphs 49-52, wherein the bacterial organism is C. bifermentans and/or C. scindens.
65. The method of any of paragraphs 49-52, wherein suppressing expression of a bacterial toxin compromises by inhibition of butyrate, codY, ccpA, tcdR, and/or tcdA production.
66. A method of suppressing expression of a bacterial toxin in the gut of a subject, the method comprising administering at least one amino acid that is metabolized by Stickland fermentation.
67. A method of treating or preventing a pathology caused by expression of a bacterial toxin, comprising administering at least one amino acid that is metabolized by Stickland fermentation.
68. The method of paragraph 66 or 67, wherein at least one amino acid is a Stickland donor or Stickland acceptor.
69. The method of paragraph 68, wherein the Stickland donor is selected from the group consisting of: alanine, leucine, valine, isoleucine, tryptophan, tyrosine and phenylalanine.
70. The method of paragraph 68, wherein the Stickland acceptor is selected from the group consisting of: glycine and proline.
71. The method of paragraph 66 or 67, wherein the amino acid is a branched-chain amino acid, a branched-keto amino acid, or an aromatic amino acid.
72. The method of paragraph 66 or 67, wherein the at least one amino acid promotes 5-aminovalerate production.
73. The method of paragraph 66 or 67, wherein the bacterial toxin is a C. difficile toxin.
74. The method of paragraph 66 or 67, wherein suppression of the expression of a bacterial toxin comprises inhibition of butyrate, codY, ccpA, tcdR, and/or tcdA activity or production.
75. A method of determining the therapeutic efficacy of a bacterial organism for treatment of a pathology involving expression of a toxin, produced by a Gram-positive spore-forming bacterium, the method comprising measuring in a biological sample obtained from an individual administered the bacterial organism one or more of: a) the amount and/or activity of a secreted proteolytic enzyme; b) the amount and/or activity of bacterial proline reductase; c) the amount or concentration of one or more branched short-chain fatty acids; d) the amount or concentration of one or more branched keto acids; and e) the amount or concentration of Stickland donor and/or Stickland acceptor amino acids and/or 5-aminovalerate; wherein measurement of an increased amount, concentration or activity of one or more of (a)-(e) relative to the amount measured in a sample taken prior to administration the bacterial organism indicates that the bacterial organism is effective for the treatment.
76. The method of paragraph 75, wherein the bacterial toxin is produced by a Gram-positive, spore-forming bacterium.
77. The method of paragraph 75, wherein the bacterial toxin is a C. difficile toxin.
78. The method of paragraph 75, wherein the pathology comprises expression of a toxin by C. difficile.
79. The method of paragraph 75, wherein Stickland donor amino acids are selected from leucine, isoleucine, valine, alanine, phenylalanine, tryptophan, tyrosine and Stickland acceptor amino acids are selected from glycine, proline, and hydroxyproline.
80. The method of paragraph 75, wherein the sample is a stool sample or a sample from within the colon of the individual.
81. A method to predict the risk of developing a disease involving a toxin produced by a Gram positive, spore-forming bacterium, the method comprising measuring in a biological sample obtained from an individual one or more of the following: a) the amount and/or activity of a secreted proteolytic enzyme; b) the amount and/or activity of bacterial proline reductase; c) the amount or concentration of one or more branched short-chain fatty acids; d) the amount or concentration of one or more branched keto acids; and e) the amount or concentration of Stickland donor and/or Stickland acceptor amino acids; and comparing the amount, concentration or activity measured in one or more of (a)-(d) to a reference, wherein an amount, concentration or activity in one or more of (a)-(d) below the reference indicates increased risk of developing a disease involving a toxin produced by a Gram positive, spore-forming bacterium.
82. The method of paragraph 81, wherein the disease involves expression of a toxin by C. difficile.
83. The method of paragraph 81, wherein the reference comprises a biological sample from a healthy individual.
84. The method of paragraph 81, wherein the biological sample is a stool sample or a sample from within the colon of the individual.
85. The method of paragraph 81, wherein two or more, of (a)-(e) are measured.
86. The method of paragraph 81, wherein three or more, of (a)-(e) are measured.
87. The method of paragraph 81, wherein four or more, of (a)-(e) are measured.
88. A method of identifying a candidate bacterial organism that is likely to suppress the expression of a toxin by a Gram-positive, spore-forming bacterial pathogen, the method comprising: a) identifying from a database of bacterial genetic information a candidate bacterial organism having in its genome: i) one or more genes encoding a secreted protease enzyme; and/or ii) a gene encoding a proline reductase enzyme; and b) assaying a sample comprising the candidate bacterial organism for the expression of a secreted protease enzyme and/or the proline reductase enzyme;
wherein the detection of expression of the secreted protease enzyme and/or the expression of the proline reductase enzyme indicates that the candidate bacterial organism is likely to suppress expression of a toxin by a Gram-positive, spore-forming bacterial pathogen.
89. The method of paragraph 88, wherein the candidate bacterial organism is not an opportunistic gut pathogen in humans.
90. The method of paragraph 88, wherein the proline reductase enzyme is an enzyme of E.C. 1.21.4.1.
91. A method to predict the risk of developing a spore-forming, toxin-producing Gram-positive bacterial pathogen in the gut or other location, or its recurrence, comprising measuring in a biological sample (a) amounts or unit activity of proteolytic activity; (b) concentrations of branched short chain fatty acids; (c) concentrations of branched keto acids; and/or (d) concentrations of Stickland donor and Stickland acceptor amino acids, wherein an increase in the amount or activity of at least one of (a)-(d) relative to a biological sample obtained prior to administration identifies a risk of developing a spore-forming, toxin-producing Gram-positive bacterial pathogen in the gut or other location.
92. The method of paragraph 91, further comprising, prior to measuring, administering the bacterial organism or amino acid to the subject.
93. The method of paragraph 91, wherein the biological sample is obtained from a subject.
94. The method of paragraph 91, wherein the biological sample is a stool sample.
95. The method of paragraph 91, wherein the biological sample is obtained from the gut.
96. The method of paragraph 91, wherein the gram-positive bacterial pathogen is C. difficile infection.
97. The composition of any of paragraphs 1-24, further comprising an amount of one or more free Stickland donor and/or Stickland acceptor amino acids effective to promote Stickland fermentation by a species in the composition or by C. difficile after the composition is administered to a subject.
98. The composition of any of paragraphs 1-24, further comprising an amount of a polypeptide substrate effective for proteolysis by proteolytic activity of a bacterial species in the composition to generate amino acids fermentable by Stickland fermentation.
99. The composition of paragraph 25, further comprising an amount of one or more free Stickland donor and/or Stickland acceptor amino acids effective to promote Stickland fermentation by a species in the composition or by C. difficile after the composition is administered to a subject.
100. The composition of paragraph 25, further comprising an amount of a polypeptide substrate effective for proteolysis by proteolytic activity of a bacterial species in the composition to generate amino acids fermentable by Stickland fermentation.
101. The composition of any one of paragraphs 98 or 100, wherein the polypeptide substrate comprises casein, collagen and/or gelatin.
102. The composition of any one of claim 98 or 100, wherein the polypeptide substrate comprises a synthetic polymer or copolymer polypeptide hydrolysable by a proteolytic activity of a species in the composition to generate Stickland fermentable amino acids.
103. The composition of paragraph 102, wherein the synthetic polymer comprises a poly[N] polymer, where N is a Stickland donor amino acid selected from leucine, isoleucine, valine, alanine, phenylalanine, tryptophan, and tyrosine or a Stickland acceptor amino acids selected from glycine and proline.
104. The composition of paragraph 102, wherein the synthetic copolymer comprises a poly[N,X] copolymer, where N and X are Stickland donor amino acids selected from leucine, isoleucine, valine, alanine, phenylalanine, tryptophan, and tyrosine or Stickland acceptor amino acids selected from glycine and proline.

EXAMPLES

Example 1: Clostridium bifermentans can Provide Complete Protection Against Fatal C. difficile Infection

(276) The technology described herein is related to the surprising discovery that two human commensal species, Clostridium scindens and Clostridium bifermentans, offer protection from an otherwise lethal infection with the Gram-positive, toxigenic bacterium, C. difficile.

(277) The effect of commensal species on the survival of mice infected with C. difficile spores was assessed using a gnotobiotic colonization model. FIG. 1A sets out the experimental approach schematically. Swiss-Webster germfree mice were pre-colonized with a commensal species (C. bifermentans, C. sardiniense or C. scindens) for 7 days, prior to challenge with 1000 spores of the C. difficile strain (ATCC43255). The survival of the mice was monitored for up to 28 days post-challenge with C. difficile (see, e.g., FIG. 1B). Body condition score (BCS) of the mice was monitored daily to assess activity, feeding, grooming and tissue turgor for additional clinical symptoms of infection (FIG. 1C).

(278) As expected, control mice that were challenged with C. difficile alone developed a severe toxin-mediated pathology and died within 5 days of the infection with the Gram-positive toxigenic bacterium C. difficile (FIG. 1B). Surprisingly, mice that were pre-colonized with the commensal species C. bifermentans were completely protected from the otherwise lethal infection with C. difficile. and showed a 100% survival rate compared to the control group infected with C. difficile without any pre-colonization treatment (FIG. 1B). Mice that were precolonized with the commensal species C. scindens showed a survival rate of 80% compared to the control group that was infected with C. difficile without any pre-colonization treatment (FIG. 1B). Precolonization with the commensal species C. sardiniense did not provide any protection against an acute infection with C. difficile (FIG. 1B).

(279) Consistent with the survival data, the body condition scores (BCS) and histopathological assessment of the mice showed that C. bifermentans provided protection against an acute primary C. difficile infection, as shown by a milder acute tissue pathology and lower lymphocytic infiltration as compared to the control group (FIG. 1C and FIG. 1G). C. bifermentans also provided protection against epithelial disruptions and tissue edema (FIG. 1G and FIG. 1J). In contrast, even though 80% of the C. scindens-colonized mice survived the infection with C. difficile, the histopathological assessment showed an increased number of inflammatory infiltrates, including a neutrophilic infiltrate, in addition to rare focal areas of epithelial denudation. Consistent with the short survival data indicating no protection against an acute primary C. difficile infection, C. sardiniense-colonized mice (FIG. 1F) developed a dilation of the colon (megacolon) with rapidly advancing tissue edema, epithelial sloughing and neutrophil efflux into the gut lumen, comparable or worse to the pathology seen in the control mice (FIG. 1E).

(280) The C. difficile biomass and levels of C. difficile toxin were examined in the gnotobiotic mouse model. C. difficile toxin B levels were assessed in cecal samples collected from germfree Swiss-Webster mice infected with 1000 spores of the C. difficile ATCC-43255 strain (FIG. 2). ToxinB was detected using an enzyme-linked immunosorbent assay (ELISA). Germ-free animals infected with C. difficile alone, C. difficile plus C. bifermentans, and C. difficile plus C. sardiniense showed that C. difficile toxin B levels in cecal contents were dramatically lower in animals pre-colonized with C. bifermentans (FIGS. 2A, 2C), but that C. sardiniense actually promoted C. difficile toxin B levels (FIG. 2A). Interestingly, examination of biomass of the individual species showed that the biomass of C. difficile in C. bifermentans pre-colonized mice was considerable despite the complete protection from death (FIG. 2B). This indicates that the protective commensal C. bifermentans involves something other than killing the C. difficile or even suppressing growth of the C. difficile organism, and indicates that C. bifermentans can instead suppress C. difficile toxin production.

(281) The effects of C. bifermentans and C. sardiniense were examined in conventional mice infected with C. difficile. FIG. 3A shows a schematic for the experiments in adult conventional mice. Briefly, adult conventional mice, with a complex gut microflora, were treated with intraperitoneal clindamycin for 24 hours before receiving 1×10.sup.4 spores of the C. difficile strain ATCC 43255. Approximately 20 hours after dosing, as mice first developed signs of symptomatic infection, animals received 5×10.sup.7 CFU of C. bifermentans, C. sardiniense or control vehicle alone by gavage, and survival was assessed for an additional 14 days. The results (shown in FIG. 3B) demonstrate that the protective effect of C. bifermentans, and the antagonistic effect of C. sardiniense is recapitulated in conventional mice, and that even in the more complex conventional mouse system, a single species of bacterium can provide complete therapeutic treatment and protection from an otherwise fatal C. difficile infection.

Example 2: Clostridium bifermentans is a Highly Proteolytic Species

(282) An examination of species that provided protective effects against C. difficile was undertaken in order to identify what characteristics of the protective species mediate the protection. Species including C. bifermentans, C. hiranonis, C. sardinense, C. scindens, C. ramosum and C. difficile clinical isolates were assessed for their proteolytic activity using both microbiological and biochemical assays. FIG. 4A shows results of a meat granule microbiological protease assay performed on C. bifermentans, C. hiranonis, C. sardiniense, C. scindens, C. ramosum and two clinical C. difficile isolates. FIG. 4B summarizes results for both microbiological and biochemical protease assays for C. difficile, C. bifermentans, C. sardiniense, and C. scindens. Clostridium bifermentans showed strikingly high proteolytic activity in the meat granule assay (FIG. 4A, 4B) and strong digestion in both gelatin and casein hydrolysis assays (FIG. 4B), while the other species were considerably less active in each of these assays (FIGS. 4A and 4B).

Example 3: Clostridium bifermentans Promotes Stickland Fermentation by the Gram-Positive Toxigenic Bacterium C. difficile

(283) The cecal contents of germfree Swiss-Webster mice were collected 20 hours after infection with C. difficile and untargeted metabolomic analysis was performed. The metabolic profiles of Stickland donor and acceptor amino acids, branched-chain amino acids (FIGS. 5A-5G) and carbohydrates (FIG. 5H) were assessed. A liquid chromatography tandem mass spectrometry (LC-MS) method was used to measure polar metabolites and, amino acids and carbohydrates in each sample. In each of FIGS. 5A-5G, the Y axis shows the Log10 MassSpec units of detected compounds. The X axis shows the experimental condition: GF-germfree controls (no bacteria); Cdiff—challenge with 1000 C. difficile spores of strain ATCC43255; CSAR—7 days mono-association with C. sardiniense; CBI—7 days mono-association with C. bifermentans; Cdiff+CSAR—mice mono-associated with C. sardiniense for 7 days followed by C. difficile challenge; Cdiff+CBI—mice mono-associated with C. bifermentans for 7 days followed by C. difficile challenge. Each group had 8 mice across two experimental replicates. Levels of amino acids/metabolites including 4-hydroxyproline (FIG. 5A), proline (FIG. 5B), 5-aminovalerate (FIG. 5C), glycine (FIG. 5D), leucine (FIG. 5E), isoleucine (FIG. 5E), valine (FIG. 5E), isovalerate (FIG. 5E), phenylalanine (FIG. 5F), tryptophan (FIG. 5F), and tyrosine (FIG. 5F), among others, were examined. The levels of the Stickland donor amino acids proline and glycine were reduced in the cecal contents of animals monoassociated with C. difficile and C. bifermentans and in animals co-colonized with C. bifermentans and C. difficile, while 5-aminovalerate, the product of reduction of proline as a Stickland donor was significantly increased in animals monoassociated with C. difficile, C. bifermentans or co-colonized with these two species. This is in contrast, for example, with the results with animals monoassociated with C. sardiniense, which was not protective, and showed levels of proline similar to those seen in germ free mice. This indicates active Stickland fermentation through the proline reductase pathway in animals colonized with C. difficile and with C. bifermentans or both. Acetate, the product of Stickland fermentation reaction through glycine as donor amino acid is produced by a number of other pathways, making it more difficult to conclude that C. bifermentans promotes Stickland fermentation through glycine. However, levels of glycine were lower than in the gut of germ free mice when mice were monoassociated with the Stickland fermenting species C. difficile and C. bifermentans, consistent with ongoing reduction of glycine through the glycine reductase Stickland pathway. The mice mono-associated with C. sardiniense for 7 days followed by C. difficile challenge also showed a 50% reduction in the levels of 5-aminovalerate (FIG. 5C), while the mice mono-associated with C. bifermentans for 7 days followed by C. difficile challenge had increased 5-aminovalerate production (FIG. 5C). Taken together, these data indicate that C. bifermentans promotes Stickland fermentation by the Gram-positive toxigenic bacterium C. difficile when C. bifermentans suppresses C. difficile toxin production.

(284) Analyses of Stickland donor amino acids including branch chain amino acids (alanine, leucine, valine, and isoleucine) and the aromatic amino acids (phenylalanine, tryptophan and tyrosine) are consistent with these amino acids participating in Stickland fermentation in C. difficile and in C. bifermentans (FIG. 5E, 5F). The products of Stickland fermentation of leucine, isoleucine and valine include the branched short chain fatty acids (bSCFA) isovalerate, isocaproate and isobutyrate, respectively. As shown in FIG. 5I, analyses of C. bifermentans metabolites showed significant production of each of these by C. bifermentans, but negligible production of butyrate, which is not a direct product of Stickland fermentation.

(285) C. difficile Short Chain Fatty Acids (SCFA) produced in in vitro culture was measured (FIG. 6A). The metabolic analysis showed that C. difficile undergoes Stickland fermentations, per branched short-chain fatty acid metabolites, and is able to also use glucose and the sugar alcohols mannitol and sorbitol (FIGS. 6A and 6B).

Example 4: Clostridium bifermentans Inhibits Expression of C. difficile Toxin Expression-Promoting Sigma Factor TcdR

(286) Gene expression was measured by bacterial RNAseq analysis of cecal contents from C. difficile infected gnotobiotic Swiss-Webster mice at 20 hours post-inoculation, compared with mice colonized with C. bifermentans for 7 days prior to challenge with C. difficile for 20 hours. C. bifermentans colonized mice showed a >48× decrease in C. difficile tcdR sigma factor gene expression with concomitant >10× decreases in toxinA (tcdA) and toxinB (tcdB) gene expression (FIG. 7), demonstrating that C. bifermentans inhibits or suppresses expression of C. difficile toxin genes. The strong repression of tcdR strongly infers codY activation and repression of the toxin gene. Similarly, the repression of tcdA and B infer codY and ccpA activation, per a nutritionally and energetically supported state to repress these genes.

Example 5: Clostridium bifermentans Promotes Expression of Genes Permitting Ethanolamine Fermentation by the Gram-Positive Toxigenic Bacterium C. difficile

(287) Gene expression was measured by bacterial RNAseq analysis of cecal contents from C. difficile-infected gnotobiotic Swiss-Webster mice at 20 hours post-inoculation, compared with mice colonized with C. bifermentans for 7 days prior to challenge with C. difficile for 20 hours. It was found that C. difficile structural proteins for the ethanolamine carboxysome (eutH, eutK, eutL, eutN) were up-regulated >10× when C. difficile is inoculated into a C. bifermentans-colonized mouse (FIG. 7). This indicates that Clostridium bifermentans likely promotes ethanolamine fermentation by the gram-positive toxigenic bacterium C. difficile.

(288) The results of the experiments described herein demonstrate that the commensal bacterium C. bifermentans not only suppresses toxin production by a mechanism involving inhibition of the C. difficile TcdR sigma factor required for C. difficile toxin expression, but also promotes Stickland fermentation by Gram-positive toxigenic bacteria such as C. difficile in vivo and thereby can treat and/or prevent the development of a toxin-mediated pathology. These in vivo activities infer specific action of C. bifermentans on the C. difficile metabolic regulators codY (primary repressor of tcdR), ccpA (repressor of the tcdAEB opeon, also of tcdR), prdR (activator of proline reductase and repressor of glycine reductase operons), and rex (sensor of NADH/NAD+ energy state). Suppression of toxin production provides an alternative route of treatment for C. difficile-mediated pathology, in that it can be sufficient for treatment to just suppress production of the pathology-generating toxin without necessarily killing the pathogenic microbe. It is contemplated that at least part of this effect is through the strong extracellular proteolytic activity expressed by C. bifermentans, in that this activity can feed amino acids necessary for the generation of energy by C. difficile through Stickland fermentation into the gut environment, thereby keeping C. difficile energetically satisfied and suppressing its expression of toxin. Another part of the effect is likely through promotion of ethanolamine metabolism for energy by C. difficile; ethanolamine derived from diet, host tissues and other commensals is fairly abundant in the gut, and a shift in C. difficile gene expression induced by C. bifermentans that permits C. difficile to gain energy from ethanolamine is contemplated to further contribute to maintaining C. difficile in an energetically satisfied state that suppresses toxin expression.