The disclosure discloses construction and application of an engineered strain of E. coli for producing malic acid by fixing CO.sub.2, and belongs to the field of fermentation. The engineered strain is obtained by performing genetic engineering transformation on Escherichia coli MG1655; the genetic engineering transformation includes knocking out a fumarate reductase gene, a fumarase gene, a lactate dehydrogenase gene and an alcohol dehydrogenase gene and freely overexpressing a formate dehydrogenase, an acetyl coenzyme A synthetase, an acylated acetaldehyde dehydrogenase, a formaldehyde lyase, a dihydroxyacetone kinase, a malic enzyme and a phosphite oxidoreductase to obtain a strain GH0407. The strain is used for producing malic acid by fermentation, anaerobic fermentation is performed for 72 hours with CO.sub.2 and glucose as a co-substrate, the production of malic acid reaches 39 g/L, the yield is 1.53 mol/mol, and accumulation of malic acid in the original strain is not achieved.

The present invention relates to a novel 3-hydroxypropionate-lactate block copolymer [P(3HP-b-LA)], and a method for preparing same, and more specifically, provides a method for preparing a 3-hydroxypropionate-lactate block copolymer, and a 3-hydroxypropionate-lactate block copolymer produced thereby, the method comprising: a first culture step in which, by using recombinant E. coli improved so as to be incapable of biosynthesizing lactic acid, P(3HP) is biosynthesized at the early stage of culturing by having glycerol as a carbon source and through 3-hydroxypropionate-generating genes and an enhanced PHA synthase; and a second culture step in which P(3HP) production is inhibited by using a carbon catabolic repression system for selectively introducing only glucose into E. coli when glycerol and glucose are supplied together as carbon sources, and in which polylactate is biosynthesized to an interrupted P(3HP) terminus by the enabling of the expression of a lactate synthase and a lactyl-CoA converting enzyme through an IPTG induction system.

The present invention relates to the field of biochemistry, specifically to the bioproduction of glycolate. Host cells, especially cyanobacteria of the genus Synechocystis, are modified in several ways to increase extracellular glycolate, including: mutant Rubisco enzymes, overexpression of phosphoribulokinase (PRK) or phosphoglycolate phosphatase (PGP), a permease to export glycolate, like GIcA, or by reduction of the capacity to metabolize glycolate due to reduced or eliminated glycolate dehydrogenase, glycolate oxidase activity and/or lactate dehydrogenase.

Provided are a novel 3-hydroxypropionate-lactate block copolymer [P(3HP-b-LA)], and a method for preparing same, comprising: a) transforming a recombinant microorganism modified to be incapable of biosynthesizing lactic acid with a vector including a 3-hydroxypropionyl-CoA biosynthesis gene and a polyhydroxyalkanoate (PHA) synthetase gene, and a vector including a lactate biosynthesis gene and a gene of an enzyme that converts lactate to lactyl-CoA; (b) synthesizing poly(3-hydroxypropionate) (P(3HP)) by culturing the recombinant microorganism using a glycerol as a carbon source; and (c) inhibiting P(3HP) production by adding IPTG and glucose, and biosynthesizing polylactate (PLA) at the end of P(3HP) synthesized in step (b) by enabling the expression of a lactate biosynthesis enzyme and an enzyme that converts lactate to lactyl-CoA. Also provided is a recombinant microorganism produced in step a).

The invention relates to a naturally hydrogen-oxidizing bacterium which is genetically modified to produce lactate from CO.sub.2, said bacterium being genetically modified to overexpress at least one gene encoding a lactate dehydrogenase, and to a process for producing lactate from CO.sub.2 using such a bacterium.

A process for producing butanol is provided, involving: A) mixing water, lactate, an enzyme mixture comprising at least one enzyme, at least one cofactor and at least one coenzyme, to prepare a reaction mixture; B) catalytically reacting the reaction mixture for an amount of time sufficient to cause conversion of lactate into butanol; and wherein the conversion of lactate into butanol in B) is associated with a regeneration system of NAD (P).sup.+/NAD (P) H and/or acetyl-CoA/CoA.

The present disclosure relates to the technical fields of genetic engineering and microbial fermentation, and discloses a recombinant strain for producing L-lactic acid, wherein the recombinant strain is obtained by genetically modifying a starting strain, the activity of D-lactate dehydrogenase of the recombinant strain is weakened or inactivated, and the activity of L-lactate dehydrogenase is enhanced, as compared with the starting strain. The present invention can significantly improve the fermentation effect, the yield of the L-lactic acid and the optical purity of the product L-lactic acid.

The present invention relates to a novel 3-hydroxypropionate-lactate block copolymer [P(3HP-b-LA)], and a method for preparing same, and more specifically, provides a method for preparing a 3-hydroxypropionate-lactate block copolymer, and a 3-hydroxypropionate-lactate block copolymer produced thereby, the method comprising: a first culture step in which, by using recombinant E. coli improved so as to be incapable of biosynthesizing lactic acid, P(3HP) is biosynthesized at the early stage of culturing by having glycerol as a carbon source and through 3-hydroxypropionate-generating genes and an enhanced PHA synthase; and a second culture step in which P(3HP) production is inhibited by using a carbon catabolic repression system for selectively introducing only glucose into E. coli when glycerol and glucose are supplied together as carbon sources, and in which polylactate is biosynthesized to an interrupted P(3HP) terminus by the enabling of the expression of a lactate synthase and a lactyl-CoA converting enzyme through an IPTG induction system.

The present invention provides D-lactate dehydrogenase, an engineered strain containing the D-lactate dehydrogenase and a construction method and use of the engineered strain. The present invention discloses a D-lactate dehydrogenase which has unique properties and is from Thermodesulfatator indicus, and the D-lactate dehydrogenase has good thermophily and heat stability. By using the D-lactate dehydrogenase and said gene engineering reconstruction method, a fermentation product of the reconstructed Bacillus licheniformis can be redirected to optically-pure D-lactic acid with a high yield from naturally produced 2,3-butanediol, and the optical purity of the produced D-lactic acid reaches 99.9%; and raw materials for fermentation are low-cost, and a fermentation state is between an anaerobic fermentation state and a microaerobic fermentation state. By using the inventive method for producing D-lactic acid through fermentation at high temperature, the production cost can be reduced, the production efficiency can be improved and there is a wide industrial application prospect for the inventive method.

Provided are a microorganism for producing a pantoic acid, and a construction method therefor and an application thereof. The microorganism for producing the pantoic acid is obtained by knocking out a gene in Escherichia coli and introducing an exogenous gene. The obtained microorganism is Escherichia coli that is registered in the China General Microbiological Culture Collection Center with an accession number of CGMCC No. 21699. A pantoic acid synthesis pathway has been opened up, and accumulation of the pantoic acid can be achieved in a fermentation process.