49 results about "Pyruvate formate lyase" patented technology

The invention discloses an XZ-A26 bacterial strain for producing L-alanine with high yield, which has a preservation number of CGMCC (China General Microbiological Culture Collection Center) No.4036 and has the capacity of generating high-concentration L-alanine through fermentation. The XZ-A26 bacterial strain is constructed by the steps of: integrating an L-alanine dehydrogenase gene on thermophilic fatty bacillus chromosome on lactic dehydrogenase position on an escherichia coli ATCC8739 chromosome, then sequentially knocking out a pyruvate formate lyase gene, an alcohol dehydrogenase gene, an acetokinase gene, a fumaric acid reductase gene and an alanine racemase gene of the escherichia coli chromosome, and then carrying out continuous cell culture in a fermenting tank for obtaining agenetic engineering strain. The invention also relates to a construction method of the XZ-A26 bacterial strain and an application of the XZ-A26 bacterial strain in preparation of the L-alanine. According to the invention, the escherichia coli with the preservation number of CGMCC No.4036 for generating the high-concentration L-alanine through fermentation can be constructed by using a metabolic engineering method, and the yield of the L-alanine generated by using the XZ-A26 bacterial strain reaches up to 115g / L. The XZ-A26 bacterial strain is suitable for industrially producing the L-alanine.

Mutants of lactic acid bacteria including Lactococcus lactis which are defective in pyruvate formate-lyase production and / or in their lactate dehydrogenase (Ldh) production and methods of isolating such mutants or variants are provided. The mutants are useful in the production of food products or in the manufacturing of compounds such as diacetyl, acetoin and acetaldehyde and as components of food starter cultures.

A thermophilic microorganism lacks lactate dehydrogenase activity and preferably contains an active pyruvate formate lyase pathway. The thermophilic microorganism contains a gene encoding an NAD-linked formate dehydrogenase. The gene encoding an NAD-linked formate dehydrogenase is preferably a codon optimised version of the gene encoding a thermostable NAD-linked formate dehydrogenase. DNA constructs allow stable expression of the gene encoding an NAD-linked formate dehydrogenase in the thermophilic microorganism. The DNA constructs are based upon use of an insertion sequence to achieve stable expression or recombination to insert the gene encoding an NAD-linked formate dehydrogenase into the lactate dehydrogenase gene, thus achieving gene knockout and new functionality in a single step. The microorganisms are useful in fermentation of sugars to produce ethanol.

The invention discloses an XZ-A26 bacterial strain for producing L-alanine with high yield, wherein the preservation number is CGMCC No.4036. The XZ-A26 bacterial strain has the ability of fermenting to produce high-concentration L-alanine and is genetic engineering bacteria prepared by integrating the L-alanine dehydrogenase gene on Escherichia Coli chromosome of a lipase gene from Geobacillus Stearothermophilus at the lactic dehydrogenase of Escherichia coli ATCC 8739 chromosome, then sequentially removing a pyruvate formate-lyase gene, an ethanol dehydrogenase gene, an acetokinase gene, a fumarate reductase gene and an alanine racemase gene of the escherichia coli chromosome and then continuously subculturing in a fermentation tank. The invention also relates to a construction method of the bacterial strain and the application of the bacterial strain in preparing the L-alanine. According to the metabolic engineering method, the escherichia coli CGMCC No.4036 capable of fermenting to produce the high-concentration L-alanineis constructed, and the yield of the L-alanine produced by fermenting the bacterial strain is as high as 115g / L. The invention is suitable for the industrial production of L-alanine.

Fermentation processes for production of ethanol include supplying a thermophilic microorganism lacking lactate dehydrogenase activity with sugars under conditions in which they metabolise them predominantly by the pyruvate-formate lyase pathway. Importantly, the processes also include supplying sufficient glycerol to convert all of the sugars to ethanol. A further embodiment of the invention includes supplying additional glycerol sufficient to convert the exogenous acetate present in biomass hydrolysates into ethanol. Any type of fermentation system can be used for these processes, but a preferred embodiment includes continuous cultures at high temperatures in which ethanol is removed continuously by vacuum evaporation.