Abstract: Related are a recombinant microorganism for producing L-valine, a construction method and an application thereof. Through enhancing amino acid dehydrogenase activity of L-valine fermentation strain, and/or activating an Entner-Doudoroff (ED) metabolic pathway, a problem in L-valine fermentation process that reducing power is unbalanced is solved, thereby the titer and yield of L-valine produced by Escherichia coli are improved, and L-valine was produced by one-step anaerobic fermentation.

Abstract: Related are a recombinant microorganism for producing L-valine, a construction method and an application thereof. Through transferring an amino acid dehydrogenase gene and/or activating activity of a transhydrogenase and/or a NAD kinase, reducing power of NADPH in cell is increased, the titer and yield of L-valine generated by Escherichia coli are improved, and the production of L-valine by one-step anaerobic fermentation is achieved.

Abstract: Related are a recombinant microorganism for producing L-valine, a construction method and an application thereof. Through transferring an acetohydroxy acid reductoisomerase gene and/or an amino acid dehydrogenase gene into a microorganism, and enhancing activity of an acetohydroxy acid reductoisomerase and/or an amino acid dehydrogenase, the titer and yield of L-valine generated by Escherichia coli may be improved, and L-valine was produced by one-step anaerobic fermentation.

Abstract: The present invention discloses an aspartase variant, method of preparing the same and use thereof. Compared with sequence 2 in the sequence listing, the amino acid sequence of the aspartase variant provided in the present invention has more than 96% identity, and there are mutations in T187I and N326C at positions 187 and 326, respectively, and has improved catalytic activity for the ammoniation of acrylic acid, compared with the aspartase shown in sequence 2. The experiment proves that the aspartase variant provided in the present invention does have improved catalytic activity for the ammoniation of acrylic acid compared with the wild type parent aspartase, and has better thermal stability and pH spectrum. The reaction can greatly increase the conversion ratio of acrylic acid.

Abstract: The present invention discloses an aspartase variant, method of preparing the same and use thereof. Compared with sequence 2 in the sequence listing, the amino acid sequence of the aspartase variant provided in the present invention has more than 96% identity, and there are mutations in T187I and N326C at positions 187 and 326, respectively, and has improved catalytic activity for the ammoniation of acrylic acid, compared with the aspartase shown in sequence 2. The experiment proves that the aspartase variant provided in the present invention does have improved catalytic activity for the ammoniation of acrylic acid compared with the wild type parent aspartase, and has better thermal stability and pH spectrum. The reaction can greatly increase the conversion ratio of acrylic acid.

Abstract: The present invention discloses a DL-alanine-producing engineering bacterium. This DL-alanine-producing engineering bacterium itself was inactivated in lactate dehydrogenase, pyruvate formate lyase, alcohol dehydrogenase, acetate kinase, fumarate reductase, alanine racemase, and methylglyoxal synthase; moreover, onto the chromosome thereof an exogenous L-alanine dehydrogenase gene and alanine racemase gene were integrated. In the present application, by integrating the exogenous L-alanine dehydrogenase gene into the chromosome of the engineering bacterium, the intermediate of glycolysis, pyruvic acid, was converted into L-alanine; by further integrating the exogenous alanine racemase gene, partial L-alanine was converted into D-alanine, achieving the direct production of DL-alanine from raw material saccharides, thereby decreasing the production cycle of DL-alanine, and increasing the yield of DL-alanine.