The invention features compositions and methods for the increased production of mevalonate, isoprene, isoprenoid precursor molecules, and/or isoprenoids in microorganisms by engineering a microorganism for increased carbon flux towards mevalonate production in the following enzymatic pathways: (a) citrate synthase, (b) phosphotransacetylase, (c) acetate kinase, (d) lactate dehydrogenase, (e) malic enzyme, and (f) pyruvate dehydrogenase such that one of more of the enzyme activity is modulated. In addition, production of mevalonate, isoprene, isoprenoid precursor molecules, and/or isoprenoids can be further enhanced by the heterologous expression of the mvaE and mvaS genes (such as, but not limited to, mvaE and mvaS genes from the organisms Listeria grayi DSM 20601, Enterococcus faecium, Enterococcus gallinarum EG2, and Enterococcus casseliflavus).

Described is a method for the production of isobutene from 3-methylcrotonyl-CoA comprising the steps of: (a) enzymatically converting 3-methylcrotonyl-CoA into 3-methylbutyric acid; and (b) further enzymatically converting the thus produced 3-methylbutyric acid into isobutene.

The conversion of 3-methylcrotonyl-CoA into 3-methylbutyric acid can be achieved by first enzymatically converting 3-methylcrotonyl-CoA into 3-methyl butyryl-CoA and further enzymatically converting the thus produced 3-methylbutyryl-CoA into 3-methylbutyric acid. Alternatively, the conversion of 3-methylcrotonyl-CoA into 3-methylbutyric acid can be achieved by first enzymatically converting 3-methylcrotonyl-CoA into 3-methylcrotonic acid and then further enzymatically converting the thus produced 3-methylcrotonic acid into 3-methylbutyric acid.

Provided are a genetically engineered strain for producing polylactic acid and a method for producing polylactic acid. The genome of the genetically engineered strain is integrated with a coding sequence of exogenous D-lactate dehydrogenase gene, a coding sequence of exogenous propionyl-CoA transferase gene, and a coding sequence of exogenous polyhydroxyalkanoate synthase gene, enabling the genetically engineered strain to express exogenous D-lactate dehydrogenase, exogenous propionyl-CoA transferase, and exogenous polyhydroxyalkanoate synthase. The method includes: providing the above genetically engineered strain of Synechococcus elongatus; introducing carbon dioxide and culturing the genetically engineered strain under light; and when a growth OD of the genetically engineered strain reaches the maximum, collecting and drying the genetically engineered strain, and recycling the polylactic acid in the strain.

The present invention provides an engineered cyanobacterium, comprising at least one plasmid selected from three novel pathways to produce acetate, which can convert atmospheric carbon dioxide as a raw material into acetate. The present invention also constructs the expression plasmid for three different transporters specific to acetate to be expressed in cyanobacteria, which comprises putative ABC transporter (AatA), succinate/acetate: proton symporter (SatP) and acetate/glycolate: cation symporter (ActP). Therefore, the engineered cyanobacteria of the present invention can produce 0.58 mg/L to 3.54 mg/L of acetate per hour.

The present invention relates to a microorganism having improved L-lysine-producing ability and an L-lysine-producing method using the same. More specifically, the present invention relates to a microorganism of the genus of Corynebacterium, in which acetate kinase activity is further enhanced over inherent activity, and an L-lysine-producing method using the same.

There is provided an acetogenic microbial cell which is capable of producing at least one higher alcohol from a carbon source, wherein the acetogenic microbial cell is genetically modified to comprise an increased expression relative to its wild type cell of at least one enzyme, E.sub.8, a butyryl-CoA:acetate CoA transferase (cat3). There is also provided a method and use of the cell to produce higher alcohols.

The present invention belongs to the bioengineering field, and relates to a method for fermentation production of L-theanine by using an Escherichia coli genetically engineered bacterium. The engineered bacterium is obtained by serving a strain as an original strain, wherein the strain is obtained after performing a single copy of T7RNAP, a dual copy of gmas, xylR knockout, and sucCD knockout on an Escherichia coli W3110 genome, and by integrating genes xfp, pta, acs, gltA, and ppc, and knocking out ackA on the genome. The present invention has a high yield, and stable production performance; after 20-25 h, L-theanine has a titer of 75-80 g/L, and the yield is up to 52-55%. The fermentation broth is purified by membrane separation in combination with a cation-anion resin series technique. Moreover, the one-step crystallization yield is 72.3% and the L-theanine final product has a purity of 99%.

The invention provides a process for reducing bio-catalytic oxidation of a product in a post-production stream. More particularly the invention provides a process for reducing bio-catalytic oxidation of an alcohol in a product stream, the product stream comprising an alcohol product, dissolved carbon dioxide, and at least one enzyme capable of oxidizing the alcohol. The invention finds applicability in fermentation processes, wherein a C1-fixing microorganism utilizes a C1-containing substrate to produce a fermentation product.

Mutant thermophilic organisms that consume a variety of biomass derived substrates are disclosed herein. Strains of Thermoanaerobacterium saccharolyticum with acetate kinase and phosphotransacetylase expression eliminated are disclosed herein. Further, strain ALK1 has been engineered by site directed homologous recombination to knockout both acetic acid and lactic acid production. Continuous culture involving a substrate concentration challenge lead to evolution of ALK1, and formation of a more robust strain designated ALK2. The organisms may be utilized for example in thermophilic SSF and SSCF reactions performed at temperatures that are optimal for cellulase activity to produce near theoretical ethanol yields without expressing pyruvate decarboxylase.

The invention relates to a genetically engineered bacterium having an enzyme that converts 3-hydroxyisovaleryl-CoA to 3-hydroxyisovalerate and an enzyme that converts 3-hydroxyisovalerate to isobutylene. Typically, the bacterium is capable of producing isobutylene from a gaseous substrate containing CO, CO.sub.2, and/or H.sub.2, such as syngas or an industrial waste gas.