Abstract: The present invention relates to a method for promoting acetylglucosamine synthesis of Bacillus subtilis, which belongs to the field of genetic engineering. The present invention adopts the recombinant Bacillus subtilis BSGNKAP2 as a starting strain, exogenously introducing pyruvate carboxylase BalpycA derived from Bacillus cereus, eliminating the central carbon metabolism overflow of the Bacillus subtilis and avoiding the synthesis of the by-product acetoin; further, five exogenous reducing force metabolic reactions are introduced to replace the reaction of generating NADH in glycolysis pathway and tricarboxylic acid cycle to reconstruct intracellular reducing force metabolism, which specifically comprise glyceraldehyde-3-phosphate ferredoxin dehydrogenase, isocitrate NAD+ dehydrogenase, a malate quinone dehydrogenase, a ketoacid ferredoxin oxidoreductase and a nitrogenase ferritin. In a shake-flask fermentation process using a complex medium, acetylglucosamine yield of the recombinant strain BSGNKAP8 is 24.

Abstract: The present invention discloses a method for producing N-acetylglucosamine (GlcNAc) by co-utilizing glucose and xylose based on CRISPRi, and belongs to the field of genetic engineering. According to the method, Bacillus subtilis BSGNY-Pveg-glmS-P43-GNA1 is used as an original strain, dCas9 induced by xylose and three sgRNA expression fragments targeting to genes zwf, pfkA and glmM respectively are integrated on the genome, and the strain is fermented in a shake flask, so that the titer of GlcNAc reaches 20.5 g/L, the yield of GlcNAc is 0.612 g/g glucose, at the same time, the efficient co-utilizing of glucose and xylose by the recombinant B.s subtilis is achieved, and the foundation for further metabolic engineering transformation of the B. Subtilis to produce GlcNAc and industrialization thereof is laid.

Abstract: The invention discloses a promoter which can be induced to express in acidic conditions, and relates to the field of bioengineering technology. The promoters of the invention are separated from A. niger and can actuate and/or regulate the expression of the effectively connected nucleic acids in A. niger. In the invention the expression of the promoters is studied in A. niger, and it is indicated that some promoters show weak expression, and some show strong activity. The invention provides an effective method and new thought for organic acids production by fungi or other products produced by fermentation under acidic conditions.

Abstract: The invention discloses a method for improving the yield of Bacillus subtilis acetylglucosamine, which belongs to the technical field of genetic engineering. In the invention, the recombinant Bacillus subtilis S5 (S5-PxylA-glmS-P43-GNA1) is taken as a starting strain, and the glmS ribozyme is integrated into the mid of rbs and the promoter sequence of the glmM and pfkA gene, respectively. The ribozyme mutant has the advantage of prolonging the stability of the mRNA and integrated into the mid of rbs and the promoter sequence of the pgi gene. The yield of GlcNAc of the recombinant strain reaches 11.79-20.05 g/L. This laid the foundation for the further metabolic engineering of Bacillus subtilis to produce GlcNAc.

Abstract: The invention discloses a promoter which can be induced to express in acidic conditions, and relates to the field of bioengineering technology. The promoters of the invention are separated from A. niger and can actuate and/or regulate the expression of the effectively connected nucleic acids in A. niger. In the invention the expression of the promoters is studied in A. niger, and it is indicated that some promoters show weak expression, and some show strong activity. The invention provides an effective method and new thought for organic acids production by fungi or other products produced by fermentation under acidic conditions.

Abstract: The present invention provides a recombinant Bacillus subtilis for producing acetylglucosamine and construction method thereof. The recombinant Bacillus subtilis is obtained by deletion of glmS ribozyme of Bacillus subtilis for regulating expression of glucosamine synthase, and insertion of a terminator and a constitutive promoter. The method comprises constructing a deleting cassette of a glmS ribozyme encoding gene, which includes an upstream homologous fragment, a resistance gene, a terminator sequence, a constitutive promoter sequence and a downstream homologous fragment in sequence; and transforming the deleting cassette into Bacillus subtilis, to obtain the recombinant Bacillus subtilis. In the invention, glucosamine synthase gene (glmS) ribozyme is deleted by homologous recombination, and in host cells, GlcN6P feedback inhibition of expression of glucosamine synthase gene glmS is blocked, and the accumulation of acetylglucosamine is improved.

Abstract: The invention discloses a method for increasing citrate production from genome reconstructed Aspergillus niger. The method is to insert a gene of low affinity glucose transporter, LGT1, to genome of A. niger. The expression level of LGT1 is under control of promoter Pgas. The genome reconstructed A. niger is tolerant to higher fermentation temperature and lower pH than that of the parental strain. Moreover, the production, yield and purity of product from reconstructed A. niger are higher than that of parental strain, and the fermentation time is shorter.

Abstract: The invention discloses a method for improving citric acid production by Aspergillus niger fermentation, which integrates Aspergillus niger GABA pathway succinate semialdehyde dehydrogenase SSD gene into Aspergillus niger genome to obtain recombinant Aspergillus niger strain, and uses recombinant black The Aspergillus strain ferments to produce citric acid; the expression of the succinate semialdehyde dehydrogenase SSD gene is regulated by the Pgas promoter. The method of the invention realizes the expression of succinate semialdehyde dehydrogenase SSD in Aspergillus niger to enhance the GABA pathway so as to strengthen the TCA cycle and promote the synthesis of citric acid.

Abstract: The present invention provides a recombinant Bacillus subtilis for producing acetylglucosamine and construction method thereof. The recombinant Bacillus subtilis is obtained by deletion of glmS ribozyme of Bacillus subtilis for regulating expression of glucosamine synthase, and insertion of a terminator and a constitutive promoter. The method comprises constructing a deleting cassette of a glmS ribozyme encoding gene, which includes an upstream homologous fragment, a resistance gene, a terminator sequence, a constitutive promoter sequence and a downstream homologous fragment in sequence; and transforming the deleting cassette into Bacillus subtilis, to obtain the recombinant Bacillus subtilis. In the invention, glucosamine synthase gene (glmS) ribozyme is deleted by homologous recombination, and in host cells, GlcN6P feedback inhibition of expression of glucosamine synthase gene glmS is blocked, and the accumulation of acetylglucosamine is improved.

Abstract: The invention discloses a promoter which can be induced to express in acidic conditions, and relates to the field of bioengineering technology. The promoters of the invention are separated from A. niger and can actuate and/or regulate the expression of the effectively connected nucleic acids in A. niger. In the invention the expression of the promoters is studied in A. niger, and it is indicated that some promoters show weak expression, and some show strong activity. The invention provides an effective method and new thought for organic acids production by fungi or other products produced by fermentation under acidic conditions.

Abstract: The invention discloses a promoter which can be induced to express in acidic conditions, and relates to the field of bioengineering technology. The promoters of the invention are separated from A. niger and can actuate and/or regulate the expression of the effectively connected nucleic acids in A. niger. In the invention the expression of the promoters is studied in A. niger, and it is indicated that some promoters show weak expression, and some show strong activity. The invention provides an effective method and new thought for organic acids production by fungi or other products produced by fermentation under acidic conditions.

Abstract: The present invention provides a method for enhancing N-acetylglucosamine production by usage of a recombinant Bacillus subtilis with a glcK knockout. This invention enhanced the production of GlcNAc by knocking out the glcK gene which encodes a glucokinase, thus eliminating the GlcNAc phosphorylation to GlcNAc-6-P. The specific growth rate and content of GlcNAc in the supernatant of the recombinant Bacillus subtilis with the glcK knockout were 0.15 h?1 and 3.0 g/L, respectively, which were 2.32 times and 2.14 times of those of the control strain without glcK knockout. The recombinant Bacillus subtilis of the present invention would be potentially useful for industrial production of GlcNAc.

Abstract: The invention provides an effective method for improving N-acetylglucosamine (GlcNAc) production by engineered B. subtilis Deletion of phosphoenolpyruvate carboxykinase encoding gene pckA and encoding pyruvate kinase gene pyK in recombinant GlcNAc-producing strain BSGNK-PxylA-glmS-P43-GNA1 (BSGNK) is first performed to enhance GlcNAc production, followed by overexpression of pyruvate carboxylase encoding gene pycA for facilitating cell growth. Finally, the GlcNAc production of the recombinant strain BPTS3 reached to 11.3 g/L, which was 1.84-fold of BSGNK. This method can be used for improve cellular property of engineered B. subtilis for GlcNAc production, which can be further applied to industrial production of GlcNAc.

Abstract: The invention discloses a promoter which can be induced to express in acidic conditions, and relates to the field of bioengineering technology. The promoters of the invention are separated from A. niger and can actuate and/or regulate the expression of the effectively connected nucleic acids in A. niger. In the invention the expression of the promoters is studied in A. niger, and it is indicated that some promoters show weak expression, and some show strong activity. The invention provides an effective method and new thought for organic acids production by fungi or other products produced by fermentation under acidic conditions.

Abstract: The invention provides an effective method for improving N-acetylglucosamine (GlcNAc) production by engineered B. subtilis Deletion of phosphoenolpyruvate carboxykinase encoding gene pckA and encoding pyruvate kinase gene pyK in recombinant GlcNAc-producing strain BSGNK-PxylA-glmS-P43-GNA1 (BSGNK) is first performed to enhance GlcNAc production, followed by overexpression of pyruvate carboxylase encoding gene pycA for facilitating cell growth. Finally, the GlcNAc production of the recombinant strain BPTS3 reached to 11.3 g/L, which was 1.84-fold of BSGNK. This method can be used for improve cellular property of engineered B. subtilis for GlcNAc production, which can be further applied to industrial production of GlcNAc.

Abstract: The present invention provides a method for enhancing N-acetylglucosamine production by usage of a recombinant Bacillus subtilis with a glcK knockout. This invention enhanced the production of GlcNAc by knocking out the glcK gene which encodes a glucokinase, thus eliminating the GlcNAc phosphorylation to GlcNAc-6-P. The specific growth rate and content of GlcNAc in the supernatant of the recombinant Bacillus subtilis with the glcK knockout were 0.15 h?1 and 3.0 g/L, respectively, which were 2.32 times and 2.14 times of those of the control strain without glcK knockout. The recombinant Bacillus subtilis of the present invention would be potentially useful for industrial production of GlcNAc.

Abstract: The invention provides a simple and effective method for improving acid tolerance of P. acidipropionici by adding arginine and/or aspartic acid to the culture medium. The acid tolerance of P. acidipropionici was improved by 60% and 20% respectively through adding arginine or aspartic acid into the culture medium. Consequently, PA production was improved by 36% and 26%, respectively. The maximal PA production was obtained by adding both 20 mM arginine and 20 mM aspartic acid. This method can be applied to large scale production of PA.

Abstract: The invention provides a simple and effective method for improving acid tolerance of P. acdipropionici by adding arginine and/or aspartic acid to the culture medium. The acid tolerance of P. acdipropionici was improved by 60% and 20% respectively through adding arginine or aspartic acid into the culture medium. Consequently, PA production was improved by 36% and 26%, respectively. The maximal PA production was obtained by adding both 20 mM arginine and 20 mM aspartic acid. This method can be applied to large scale production of PA.

Abstract: Disclosed are methods for increasing microbial catalase production. 1-10 g/L sodium hexametaphosphate was added to the culture medium between 30-40 hours of fermentation to inhibit proteinase activity and increase the production of catalase. This simple modification of fermentation procedure can result in up to 45% increase of the production of catalase.

Abstract: The present invention discloses a method and a system for log file analysis based on distributed computing network. The method includes: storing user identifiers and related log information into a log file; dividing the log file into target files each including the log information having the same user identifier; separately analyzing the target files to obtain analysis results using at least two nodes; and combining the analysis results of the nodes. The method thereby establishes relationships among various log files through user identifiers, and further analyzes the relationships among the user's accesses to various contents of a website.