Abstract: The present invention discloses a formate dehydrogenase mutant with improved enzyme activity and stability and a construction method thereof, which belongs to the technical field of genetic engineering. The mutant of the present invention is obtained by mutating alanine at a 10th site to cysteine based on the amino acid shown in SEQ ID NO. 2. The specific enzyme activity of the mutant enzyme obtained by the present invention is improved by 1.3 times compared with that before the mutation, a half-life period (t1/2) at 60° C. is increased by 6.8 times compared with that in the mutation period, the copper ion tolerance is increased by 30 times compared with that before the mutation, and when pH is 4, the stability is improved by 2.0 times, and the catalytic efficiency is increased by 1.4 times.

Abstract: The present invention discloses a single-cell factory for efficiently synthesizing ?-aminobutyric acid and construction and application thereof, which belong to the technical field of microorganisms. The present invention expresses an L-threonine deaminase gene, an L-amino acid dehydrogenase gene and a dehydrogenase gene for providing cofactor NADH cycle in tandem to construct a recombinant Escherichia coli single-cell factory which is used for efficiently synthesizing ?-aminobutyric acid. The expression level of the L-threonine deaminase is optimized and controlled by an RBS sequence, so that the problem of transformation inhibition caused by the rapid accumulation of an intermediate product ketobutyric acid is solved, moreover, the expression level of the dehydrogenase for providing cofactor NADH cycle is optimized and controlled by a promoter and an RBS sequence, consequently, the NADH regeneration rate is increased, and ultimately, yield is increased.

Abstract: The present invention relates to application of a novel signal peptide in L-arginine and its derivatives production from konjac powder, which belongs to the field of gene engineering, enzyme engineering and metabolism engineering. The present invention fused the signal peptide set forth in SEQ ID NO.1 with the ?-mannanase of Bacillus subtilis CCTCC M 209200, and expressed the fused gene in the strain with high L-arginine yield. The recombinant strain Corynebacterium crenatum CGMCC 0890/p MSPman had advantages on utilizing cheaper konjac powder as substrate, and after fermenting for 96 hours in a 5 L bioreactor, the L-arginine yield reached 45 g/L. Another two recombinant strains were constructed based on Corynebacterium crenatum CGMCC 0890/pMSPman, and after fermenting for 96 hours in a 5 L bioreactor, the L-ornithine yield and L-citrulline reached 23.5 g/L and 26.3 g/L respectively.

Abstract: The present invention relates to application of a novel signal peptide in L-glutamate and its derivatives production from konjac powder, which belongs to the field of gene engineering, enzyme engineering and metabolism engineering. The signal peptide which mediated secretion of ?-mannanase was invented, and the recombinant strain with this signal peptide had advantages on utilizing konjac powder to produce related products, and its utilization efficiency of konjac powder, production efficiency, and yield were higher than other signal peptides. The recombinant strain possessing this new signal peptide had advantages on utilizing cheaper konjac powder as substrate to lower the process costs on L-glutamic acid and its high-value-added products.

Abstract: The present invention discloses a single-cell factory for efficiently synthesizing ?-aminobutyric acid and construction and application thereof, which belong to the technical field of microorganisms. The present invention expresses an L-threonine deaminase gene, an L-amino acid dehydrogenase gene and a dehydrogenase gene for providing cofactor NADH cycle in tandem to construct a recombinant Escherichia coli single-cell factory which is used for efficiently synthesizing ?-aminobutyric acid. The expression level of the L-threonine deaminase is optimized and controlled by an RBS sequence, so that the problem of transformation inhibition caused by the rapid accumulation of an intermediate product ketobutyric acid is solved, moreover, the expression level of the dehydrogenase for providing cofactor NADH cycle is optimized and controlled by a promoter and an RBS sequence, consequently, the NADH regeneration rate is increased, and ultimately, yield is increased.

Abstract: The present invention discloses a formate dehydrogenase mutant with improved enzyme activity and stability and a construction method thereof, which belongs to the technical field of genetic engineering. The mutant of the present invention is obtained by mutating alanine at a 10th site to cysteine based on the amino acid shown in SEQ ID NO. 2. The specific enzyme activity of the mutant enzyme obtained by the present invention is improved by 1.3 times compared with that before the mutation, a half-life period (t1/2) at 60° C. is increased by 6.8 times compared with that in the mutation period, the copper ion tolerance is increased by 30 times compared with that before the mutation, and when pH is 4, the stability is improved by 2.0 times, and the catalytic efficiency is increased by 1.4 times.

Abstract: The present invention relates to application of a novel signal peptide in L-arginine and its derivatives production from konjac powder, which belongs to the field of gene engineering, enzyme engineering and metabolism engineering. The present invention fused the signal peptide set forth in SEQ ID NO.1 with the ?-mannanase of Bacillus subtilis CCTCC M 209200, and expressed the fused gene in the strain with high L-arginine yield. The recombinant strain Corynebacterium crenatum CGMCC 0890/p MSPman had advantages on utilizing cheaper konjac powder as substrate, and after fermenting for 96 hours in a 5 L bioreactor, the L-arginine yield reached 45 g/L. Another two recombinant strains were constructed based on Corynebacterium crenatum CGMCC 0890/pMSPman, and after fermenting for 96 hours in a 5 L bioreactor, the L-ornithine yield and L-citrulline reached 23.5 g/L and 26.3 g/L respectively.

Abstract: The present invention relates to application of a novel signal peptide in L-glutamate and its derivatives production from konjac powder, which belongs to the field of gene engineering, enzyme engineering and metabolism engineering. The signal peptide which mediated secretion of ?-mannanase was invented, and the recombinant strain with this signal peptide had advantages on utilizing konjac powder to produce related products, and its utilization efficiency of konjac powder, production efficiency, and yield were higher than other signal peptides. The recombinant strain possessing this new signal peptide had advantages on utilizing cheaper konjac powder as substrate to lower the process costs on L-glutamic acid and its high-value-added products.