The present invention provides a method for producing 2-methyl-butyric acid by fermentation using a bacterium belonging to the order Enterobacterales which has been modified to attenuate expression of a tyrB gene encoding a protein having tyrosine aminotransferase activity. The method also allows for production of a byproduct substance of 2-methyl-butyric acid during fermentation of the Enterobacterales bacterium having 2-methyl-butyric acid-producing ability.

The present invention provides a method for producing 2-methyl-butyric acid by fermentation using a bacterium belonging to the order Enterobacterales which has been modified to attenuate expression of a tyrB gene encoding a protein having tyrosine aminotransferase activity. The method also allows for production of a byproduct substance of 2-methyl-butyric acid during fermentation of the Enterobacterales bacterium having 2-methyl-butyric acid-producing ability.

The disclosure relates to engineered enone reductase polypeptides having improved properties, polynucleotides encoding the engineered polypeptides, related vectors, host cells, and methods for making the engineered enone reductase polypeptides. The disclosure also provides methods of using the engineered enone reductase polypeptides for chemical transformations.

The disclosure relates to engineered enone reductase polypeptides having improved properties, polynucleotides encoding the engineered polypeptides, related vectors, host cells, and methods for making the engineered enone reductase polypeptides. The disclosure also provides methods of using the engineered enone reductase polypeptides for chemical transformations.

A process includes providing a gaseous substrate comprising CO.sub.2 to a bioreactor; providing acetogenic bacteria and medium to the bioreactor to provide a fermentation broth; providing sodium ions to the bioreactor through one or more sodium ion sources; fermenting the gaseous substrate with the acetogenic bacteria in the fermentation broth to produce one or more organic acids; and controlling a butyric acid to an acetic acid ratio by controlling the pH of the fermentation broth. In one aspect, butyric acid to acetic acid ratio increases when the pH of the fermentation broth decreases, and the ratio of butyric acid to acetic acid concentration decreases when the pH of the fermentation broth increases. The acetogenic bacteria includes a sodium translocating ATPase that is active during fermentation in the bioreactor. The sodium ions are provided so that Na.sup.+ is maintained between 1000 to 11000 ppm (g/g) in culture broth.

A process includes providing a gaseous substrate comprising CO.sub.2 to a bioreactor; providing acetogenic bacteria and medium to the bioreactor to provide a fermentation broth; providing sodium ions to the bioreactor through one or more sodium ion sources; fermenting the gaseous substrate with the acetogenic bacteria in the fermentation broth to produce one or more organic acids; and controlling a butyric acid to an acetic acid ratio by controlling the pH of the fermentation broth. In one aspect, butyric acid to acetic acid ratio increases when the pH of the fermentation broth decreases, and the ratio of butyric acid to acetic acid concentration decreases when the pH of the fermentation broth increases. The acetogenic bacteria includes a sodium translocating ATPase that is active during fermentation in the bioreactor. The sodium ions are provided so that Na.sup.+ is maintained between 1000 to 11000 ppm (g/g) in culture broth.

In a method for preparing a keto acid, an enzymatic reaction is carried out by using glycine and an alcoholic organic substance as substrates; the alcoholic organic substance is converted into an aldehyde organic substance, glycine and the aldehyde organic substance are converted into a -hydroxy--amino acid, and then the -hydroxy--amino acid is converted into a keto acid. The preparation method for a keto acid can also be used in the preparation of amino acids. The number of enzymes used is much less than that of enzymes used in a natural synthesis route, so that the production cost is low. An artificial metabolism platform for keto acids is established and can produce multiple important keto acids, such as phenylpyruvic acid, 4-methyl-2-oxopentanoic acid, pyruvic acid and 2-oxo-butyric acid.

Provided is a Lactobacillus casei producing short-chain fatty acids in a high yield, a culture method therefor and an application thereof. Lactobacillus casei LC89 capable of producing short-chain fatty acids in a high yield is preserved in the China General Microbiological Culture Collection Center on 5 Mar. 2018, with the accession number of CGMCC NO. 15409 and a classification name of Lactobacillus casei. Provided is a Lactobacillus casei producing short-chain fatty acids in a high yield, which is superior to the commercial strain, Lactobacillus rhamnosus GG (LGG). Also provided are a cultivation method therefor and an application thereof in the treatment of host inflammatory bowel diseases to achieve functions of supplementing probiotics to regulate the intestinal tract and alleviating host inflammatory bowel diseases.

Provided is a Lactobacillus casei producing short-chain fatty acids in a high yield, a culture method therefor and an application thereof. Lactobacillus casei LC89 capable of producing short-chain fatty acids in a high yield is preserved in the China General Microbiological Culture Collection Center on 5 Mar. 2018, with the accession number of CGMCC NO. 15409 and a classification name of Lactobacillus casei. Provided is a Lactobacillus casei producing short-chain fatty acids in a high yield, which is superior to the commercial strain, Lactobacillus rhamnosus GG (LGG). Also provided are a cultivation method therefor and an application thereof in the treatment of host inflammatory bowel diseases to achieve functions of supplementing probiotics to regulate the intestinal tract and alleviating host inflammatory bowel diseases.

Biocatalytic conversion systems and methods of producing and using same that have improved yields are disclosed. The systems and methods involve co-fermentation of sugars and gaseous substrates for alcohol, ketone, and/or organic acid production. The systems and methods may include biocatalytically converting at least one sugar substrate into at least one of alcohol, at least one ketone, and/or at least one organic acid. The systems and methods may further include biocatalytically converting gases that comprise CO.sub.2 and H.sub.2 to at least one alcohol and/or at least one organic acid, thereby adding extra revenue to biorefineries.