48 results about "Pyruvate formate lyase" patented technology

A method for isolating succinic acid producing bacteria is provided comprising increasing the biomass of an organism which lacks the ability to catabolize pyruvate, and then subjecting the biomass to glucose-rich medium in an anaerobic environment to enable pyruvate-catabolizing mutants to grow.The invention also provides for a mutant that produces high amounts of succinic acid, which has been derived from a parent which lacked the genes for pyruvate formate lyase and lactate dehydrogenase, and which belongs to the E.coli Group of Bacteria.

The invention provides a genetically engineered bacterium for high-yielding L-valine. A construction method of the genetically engineered bacterium comprises the steps that starting from an escherichia coli W3110, an acetolactate synthase gene alsS of a bacillus subtilis is integrated on a genome of the escherichia coli W3110 and subjected to high expression; an escherichia coli ppGpp 3'-pyrophosphoric acid hydrolytic enzyme mutant R290E/K292D gene spoT is integrated on the genome of the escherichia coli W3110 and subjected to high expression; genes of frdA, frdB, frdC and frdD of four subunits of a lactic dehydrogenase gene ldhA, a pyruvate formate lyase I gene pflB and fumaric reductase on the genome of the escherichia coli W3110 are knocked out; a branched chain amino acid transaminasegene ilvE of the escherichia coli is replaced with leucine dehydrogenase gene bcd of the bacillus subtilis; and an acetyl-hydroxyl acid isomerized reductase gene ilvC of the escherichia coli is replaced with an encoding gene of a mutant L67E/R68F/K75E. According to the genetically engineered bacterium for the high-yielding L-valine, an L-valine fermentation method is further modified. Double-phasedissolved oxygen control is adopted, and the L-valine yield and the saccharic acid conversion rate are improved.

The present invention relates to novel rumen bacterial mutants resulted from the disruption of a lactate dehydrogenase gene (ldhA) and a pyruvate formate-lyase gene (pfl) (which are involved in the production of lactic acid, formic acid and acetic acid) from rumen bacteria; a novel bacterial mutant (Mannheimia sp. LPK7) having disruptions of a lactate dehydrogenase gene (ldhA), a pyruvate formate-lyase gene (pfl), a phosphotransacetylase gene (pta), and a acetate kinase gene (ackA); a novel bacterial mutant (Mannheimia sp. LPK4) having disruptions of a lactate dehydrogenase gene (ldhA), a pyruvate formate-lyase gene (pfl) and a phosphoenolpyruvate carboxylase gene (ppc) involved in the immobilization of CO2 in a metabolic pathway of producing succinic acid; and a method for producing succinic acid, which is characterized by the culture of the above mutants in anaerobic conditions. The inventive bacterial mutants have the property of producing succinic acid at high concentration while producing little or no organic acids, as compared to the prior wild-type strains of producing various organic acids. Thus, the inventive bacterial mutants are useful as strains for the industrial production of succinic acid.

The invention discloses a strain of engineering bacteria producing DL-alanine. Lactic dehydrogenase, pyruvate formate lyase, alcohol dehydrogenase, acetic acid kinase, fumaric acid reductase, alanine racemase and methyl glyoxal synthetase of the strain of engineering bacteria producing the DL-alanine are inactivated; and exogenous L-alanine dehydrogenase gene and alanine racemase gene are integrated on the chromosome of the engineering bacteria. According to the invention, pyroracemic acid, an intermediate product of the glycolysis is converted to L-alanine by integrating the exogenous L-alanine dehydrogenase gene into the chromosome of the engineering bacteria; and an exogenous alanine racemase gene is further integrated into the chromosome, and part of the L-alanine is converted into D-alanine. Then producing the DL-alanine from raw material sugar in one step is realized, the production period of the DL-alanine is decreased and the productivity of the DL-alanine is enhanced.

Methods of enhancing the growth rate and/or controlling the metabolic activity of lactic acid bacteria and of improving the shelf life and/or the quality of an edible product using lactic acid bacterial organisms which are defective in their pyruvate metabolism. There is also provided starter culture compositions comprising such defective lactic acid bacteria as helper organisms and lactic acid bacterial starter culture strains. Useful helper organisms are Lactococcus strains which are defective with respect to pyruvate formate lyase (Pfl) and/or lactate dehydrogenase (Ldh) activity. The helper organisms may overexpress a gene coding for an NAD+ regenerating enzyme such as NADH oxidase encoded by nox gene.

The invention relates to an ethanol fermentation engineering bacteria capable of reducing a fermentation byproduct. The ethanol fermentation engineering bacteria is characterized in that a pyruvate formate-lyase gene and a lactate dehydrogenase gene of Escherichia coli are inactivated; and a Zymomonas mobilis gene is transferred into the Escherichia coli. When ethanol is produced by fermenting hexose and pentose with the engineering bacteria, lactic acid and formic acid are not produced and the byproduct is reduced, so that the ethanol productivity is improved.

A method for producing D-lactic acid in high yield, and to provide a method for producing D-lactic acid with high selectivity, in which optical purity is high and a by-product organic acid is small. In one aspect, a microorganism, wherein activity of pyruvate formate-lyase (pfl) is inactivated or decreased, and further activity of Escherichia coli-derived NADH-dependent D-lactate dehydrogenase (ldhA) is enhanced, is cultured to efficiently produce D-lactic acid. With regard to a method for enhancing ldhA activity, by linking, on a genome, a gene encoding ldhA with a promoter of a gene which controls expression of a protein involved in a glycolytic pathway, a nucleic acid biosynthesis pathway or an amino acid biosynthesis pathway, suitable results are obtained compared to the method for enhancing expression of the gene using an expression vector. A microorganism in which a dld gene is substantially inactivated or decreased is cultured to produce high quality D-lactic acid with reduced concentration of pyruvic acid.

The present invention relates to novel rumen bacterial mutants resulted from the disruption of a lactate dehydrogenase gene (ldhA) and a pyruvate formate-lyase gene (pfl) (which are involved in the production of lactic acid, formic acid and acetic acid) from rumen bacteria; a novel bacterial mutant (Mannheimia sp. LPK7) having disruptions of a lactate dehydrogenase gene (ldhA), a pyruvate formate-lyase gene (pfl), a phosphotransacetylase gene (pta), and a acetate kinase gene (ackA); a novel bacterial mutant (Mannheimia sp. LPK4) having disruptions of a lactate dehydrogenase gene (ldhA), a pyruvate formate-lyase gene (pfl) and a phosphoenolpyruvate carboxylase gene (ppc) involved in the immobilization of CO2 in a metabolic pathway of producing succinic acid; and a method for producing succinic acid, which is characterized by the culture of the above mutants in anaerobic conditions. The inventive bacterial mutants have the property of producing succinic acid at high concentration while producing little or no organic acids, as compared to the prior wild-type strains of producing various organic acids. Thus, the inventive bacterial mutants are useful as strains for the industrial production of succinic acid.

The present invention relates to a mutant microorganism, which is selected from the group consisting of genus Mannheimia, genus Actinobacillus and genus Anaerobiospirillum, producing homo-succinic acid and a method for producing homo-succinic acid using the same, and more particularly to a mutant microorganism producing succinic acid at a high concentration while producing little or no other organic acids in anaerobic conditions, which is obtained by disrupting a gene encoding lactate dehydrogenase (ldhA), a gene encoding phosphotransacetylase (pta), and a gene encoding acetate kinase (ackA), without disrupting a gene encoding pyruvate formate lyase (pfl), as well as a method for producing succinic acid using the same. The inventive mutant microorganism has the property of having a high growth rate and succinic acid productivity while producing little or no organic acids, as compared to the prior strains producing succinic acid. Thus, the inventive mutant microorganism is useful to produce succinic acid for industrial use.

The invention belongs to the field of biology engineering technology, and relates to a genetic engineering strain for producing succinic acid by utilizing glucose and an acidogenic fermentation method of the genetic engineering strain. The genetic engineering strain for producing succinic acid by utilizing glucose is named as Escherichia coli BA205 and the preservation number is registered as CCTCC No.M2011447. In the construction process, Escherichia coli which is short of lactic dehydrogenase (LDH) gene and Pyruvate formate-lyase (PFL) gene activity is mainly used as an original strain; phosphoenolpyruvate carboxylase (PPC) gene is removed by utilizing a homologous recombination technology; and phosphoenolpyruvate carboxylase and nicotinic acid phosphoribosyl transferase are excessively co-expressed; therefore the synthesis efficiency of succinic acid is greatly increased. In the fermentation method, a two-stage fermentation manner is adopted, the biomass is improved in an aerobic stage and the acidogenic fermentation is carried out in an anaerobic stage.

The invention discloses a recombination strain for an enterobacterium and application of the recombination strain for the enterobacterium. The recombination strain provided by the invention is a recombination strain obtained after deactivation of a pyruvate formate-lyase gene in the enterobacterium. As shown by experiments, the amount of by-product CO2 produced during the fermentation process of the recombination strain is obviously reduced and the amount of target products is obviously improved compared with the prior art. For example, the amount of lactic acid, the amount of succinic acid and the amount of 2, 3-butanediol produced by fermentation of klebsiella oxytoca are respectively improved by 30 percent, 9 percent and 23 percent compared with the prior art, and the amount of the CO2 produced is only 8.04 percent compared with the prior art. The recombination strain helps to release the pressure of the greenhouse effect, has important function in the actual industrial production, not only can greatly reduce the yield of the CO2 but also can improve the conversion rate of converting substrates into products, and has wide application prospect.

The invention discloses engineering bacteria for knocking out pyruvate formate-lyase genes and an application of the engineering bacteria. The pyruvate formate-lyase (flpB) genes in a wild-type strain for producing 1,3-propanediol are knocked out by utilizing a gene homologous recombination and gene insertional inactivation method, so that the gene engineering bacteria with blocked metabolic pathways of methanoic acid can be obtained. The engineering bacteria are used for fermenting production of 1,3-propanediol, and the synthesis of the byproduct methanoic acid is greatly reduced, so that the toxicity effect of the methanoic acid for cells can be reduced, and the concentration, production intensity and substrate conversion rate of the 1,3-propanediol can be improved. The experiment shows that when the engineering bacteria are fermented for 32h in a conventional method, the synthesis amount of the methanoic acid is reduced by more than 90 percent, and the concentration of the 1, 3-propanediol can reach more than 72g/L. By adopting the engineering bacteria, the progress of the technology for producing the 1,3-propanediol in the microorganism fermentation method can be promoted, and the application value can be realized.

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.