A fermentation process includes contacting a starch hydrolysate with a glucoamylase with agitation. And allowing for settling to form a multi-phase solution. A first phase of the multi-phase solution includes a saccharide component comprising about 30 wt % to about 80 wt % (e.g., 30 wt % to 70 wt %, 30 wt % to 60 wt %) based on a total carbohydrate present. The method further includes draining the first phase to isolate the first phase from a second phase to form a fermentation broth comprising a first portion of the first phase. The method further includes fermenting the fermentation broth until a concentration of glucose in the fermentation broth is 40 g/L or less. The method includes adding a second portion of the first phase to the fermentation broth to maintain a concentration of glucose in a range of from about 1 g/L to about 20 g/L in the fermentation broth.

The technology provided herein relates to novel methods for producing lactic acid (L-lactic acid, D-lactic acid and D/L-Lactic acid) from starch containing material with extreme thermophilic bacterial cells belonging to the genus Caldicellulosiruptor, mutants thereof, isolated strains, microbial cultures, and microbial compositions. The novel methods are in particular suitable for the production of lactic acid from any carbon source, not limited to but especially useful for unmodified starch and/or starch-containing material.

The technology provided herein relates to novel methods for producing lactic acid (L-lactic acid, D-lactic acid and D/L-Lactic acid) from starch containing material with extreme thermophilic bacterial cells belonging to the genus Caldicellulosiruptor, mutants thereof, isolated strains, microbial cultures, and microbial compositions. The novel methods are in particular suitable for the production of lactic acid from any carbon source, not limited to but especially useful for unmodified starch and/or starch-containing material.

Induction mutagenesis in lactic acid bacteria for D(−) lactic acid production from starch was performed and the stable mutant strain of Lactobacillus plantarum improved by the molecular biological technique can be used in production of high optically pure D(−) lactic acid directly from various kinds of starch as a carbon source. Those starch substrates are included cassava starch, corn starch and rice starch, etc. The fermentation product is high optically pure D(−) lactic acid up to 90.0-99.0% which is able to apply in bioplastic and pharmaceutical industries.

Induction mutagenesis in lactic acid bacteria for D(−) lactic acid production from starch was performed and the stable mutant strain of Lactobacillus plantarum improved by the molecular biological technique can be used in production of high optically pure D(−) lactic acid directly from various kinds of starch as a carbon source. Those starch substrates are included cassava starch, corn starch and rice starch, etc. The fermentation product is high optically pure D(−) lactic acid up to 90.0-99.0% which is able to apply in bioplastic and pharmaceutical industries.

A batch fermentation process ferments a starch hydrolysate containing 80-98 weight percent of glucose based on total carbohydrate and 0.3-5% weight percent of isomaltose based on total carbohydrate to a fermentation product. A fermentation broth is formed containing a first portion of a total amount of the starch hydrolysate so that the fermentation broth has an initial glucose concentration of at least about 50 g/L. Fermentaion is carried out until the fermentation broth contains 30 g/L or less of glucose. An effective amount of at least one active enzyme that converts isomaltose into glucose is adding to the fermentation broth. Then the remaining portion of the total amount of starch hydrolysate is fed into the fermentation broth to maintain a glucose concentration of from about 5 to about 15 g/L in the fermentation broth throughout the feeding step. The final fermentation broth containing the fermentation product is then produced.

A batch fermentation process ferments a starch hydrolysate containing 80-98 weight percent of glucose based on total carbohydrate and 0.3-5% weight percent of isomaltose based on total carbohydrate to a fermentation product. A fermentation broth is formed containing a first portion of a total amount of the starch hydrolysate so that the fermentation broth has an initial glucose concentration of at least about 50 g/L. Fermentaion is carried out until the fermentation broth contains 30 g/L or less of glucose. An effective amount of at least one active enzyme that converts isomaltose into glucose is adding to the fermentation broth. Then the remaining portion of the total amount of starch hydrolysate is fed into the fermentation broth to maintain a glucose concentration of from about 5 to about 15 g/L in the fermentation broth throughout the feeding step. The final fermentation broth containing the fermentation product is then produced.

The present disclosure provides novel bacterial strains with altered expression or start codon modification of one or more RNA degradation/processing genes. The RNA degradation genes of the present disclosure are controlled by heterologous promoters. The present disclosure further describes methods for generating microbial strains comprising heterologous promoter sequences operably linked to RNA degradation/processing genes.

The present disclosure provides novel bacterial strains with altered expression or start codon modification of one or more RNA degradation/processing genes. The RNA degradation genes of the present disclosure are controlled by heterologous promoters. The present disclosure further describes methods for generating microbial strains comprising heterologous promoter sequences operably linked to RNA degradation/processing genes.

Disclosed is a technique for constructing optogenetic amplifier and inverter circuits utilizing transcriptional activator/repressor pairs, in which expression of the transcriptional activator or repressor, respectively, is controlled by light-controlled transcription factors. This system is demonstrated utilizing the quinic acid regulon system from Neurospora crassa, or Q System, a transcriptional activator/repressor system. This is also demonstrated utilizing the galactose regulon from Saccharomyces cerevisiae, or GAL System. Such optogenetic amplifier circuits enable multi-phase microbial fermentations, in which different light schedules are applied in each phase to dynamically control different metabolic pathways for the production of proteins, fuels or chemicals. The orthogonal nature of the Q and GAL systems enable the co-expression of amplifier and inverter circuits to simultaneously amplify and invert the response of light-controlled transcriptional controls over different sets of genes in the same cell.