6results about How to "Reduce feedback inhibition" patented technology

The invention relates to the technical production field of metabolic engineering and genetic engineering, and particularly provides a genetically engineered bacterium for producing 2 '-deoxyuridine as well as a construction method and application of the genetically engineered bacterium. According to the strain, deoxyuridine kinase tdk is knocked out on an E.coli W3110 genome, and T7 RNA polymerase is integrated; an aspartate transaminase gene aspC, a glutamine synthetase gene glnA, a 5 '-deoxynucleotidase gene yfbR and a uridine monophosphate kinase gene pyrH are subjected to overexpression; the method comprises the following steps: introducing a ribonucleoside diphosphate reductase gene nrdBCA from Escherichia phage T4 in a heterologous series connection manner; the CTP synthase gene pyrG * of Corynebacterium glutamicum is introduced in a heterologous mode, and the CTP synthase gene pyrG * of Corynebacterium glutamicum is introduced in a heterologous mode. The safe, efficient and low-cost production of the 2 '-deoxyuridine is realized.

This application relates to the fields of genetic engineering and enzyme engineering, specifically to an ornithine decarboxylase mutant, gene, recombinant plasmid, recombinant strain, and its applications. The ornithine decarboxylase mutant is obtained by mutating the wild-type ornithine decarboxylase with the amino acid sequence shown in SEQ ID NO.1, and the mutation sites of the ornithine decarboxylase mutant include any one or more of Y104F, A264V, Q263E, R157K, S325C, and V265A. By performing single-point or multi-site combination mutations on the wild-type ornithine decarboxylase, a high-activity ornithine decarboxylase mutant is obtained, thereby significantly improving the substrate conversion rate of the ornithine decarboxylation reaction and the synthesis efficiency of butanediamine. This successfully overcomes the rate-limiting bottleneck of the ornithine decarboxylation reaction in the synthetic pathway from glucose to ornithine and then to butanediamine, significantly optimizing the overall efficiency of this metabolic pathway.

This invention is a divisional application for "Ornithine Decarboxylase Mutant, Gene, Recombinant Plasmid, Recombinant Strains and Applications," relating to the fields of genetic engineering and enzyme engineering technology, specifically involving an ornithine decarboxylase mutant, gene, recombinant plasmid, recombinant strain, and applications. The ornithine decarboxylase mutant is obtained by mutating the wild-type ornithine decarboxylase with the amino acid sequence shown in SEQ ID NO.1, and the mutation site of the ornithine decarboxylase mutant is Y104F. By performing single-point or multi-site combination mutations on the wild-type ornithine decarboxylase, a high-activity ornithine decarboxylase mutant is obtained, thereby significantly improving the substrate conversion rate of the ornithine decarboxylation reaction and the synthesis efficiency of butanediamine. This successfully overcomes the rate-limiting bottleneck of the ornithine decarboxylation reaction in the synthetic pathway from glucose to ornithine and then to butanediamine, significantly optimizing the overall efficiency of this metabolic pathway.

The present invention discloses a method for producing nicotinamide mononucleotide by double enzyme "one-pot method". The method is carried out under the optimal conditions: 25 mg / mL EBY-NRK, 10 mg / mL EBY-PPK, 5mM NR, 1.5 mM ATP, 15 mM phosphate donor, 2 mM Mg-containing 2+ The material can catalyze the production of 82.8% NMN at 30°C and pH 6.5, and the ATP cost is reduced by 75%. The whole-cell enzyme preparation retains more than 50% enzyme activity after being reused 5 times. The present invention also developed a whole-cell catalyst displayed on the surface of recombinant yeast, which solves the problem of byproduct accumulation feedback inhibition conversion during NMN biosynthesis by coupling the ATP regeneration system, achieving a good NMN product generation rate while effectively reducing costs.

The invention provides a production method of D-pantothenic acid. The production method of the D-pantothenic acid comprises the following steps: continuously fermenting an escherichia coli strain in a culture medium to produce the D-pantothenic acid, wherein the concentration of the escherichia coli strain is 40-50g / L; the pH value of the continuous fermentation is 6.5-7.0. According to the production method of the D-pantothenic acid, the production efficiency of the D-pantothenic acid is greatly improved, and the application prospect is good.

The present invention relates to a method for culturing an oxygen-resistant Lactobacillus acidophilus, the method comprising: culturing the activated Lactobacillus acidophilus in a microbial droplet culture instrument, using hydrogen peroxide as an oxygen stress factor in the culture to obtain Lactobacillus acidophilus droplets; purifying the Lactobacillus acidophilus droplets, inoculating them into a fermentation medium after activation, and fermenting them under the condition of introducing air. The method described in the present application can improve the domestication efficiency and accuracy of Lactobacillus acidophilus, reduce the feedback inhibition of metabolites on lactic acid bacteria, and improve the tolerance of lactic acid bacteria to oxygen, so as to achieve the purpose of high-density fermentation under aerobic conditions.