Abstract: The present disclosure provides a preparation method of a yak hide-derived oligopeptide ferrous chelate with a high antioxidant activity. The preparation method includes preparing a yak hide-derived oligomeric collagen peptide and subjecting the yak hide-derived oligomeric collagen peptide as a protein source to chelation with an iron source in water. A pretreated yak hide is subjected to enzymatic hydrolysis under a pH value of 7 at 50° C. for 4 h with an amount of an enzyme added at 2% to obtain a yak skin-derived collagen with a molecular weight of less than 2 kDa; the chelation is conducted in a peptide-to-iron mass ratio of 1:1 to 5:1 with a peptide concentration of 1% to 5% at 30° C. to 70° C. for 20 min to 60 min under a pH value of 3 to 8; and an iron chelating capacity is 42.72 mg/g under optimal preparation conditions.

Abstract: A method for extracting pullulan polysaccharide from high-viscosity fermentation broth includes following steps: (1) removing cells from the fermentation broth; (2) removing proteins; (3) decolorizing by macroporous resin adsorption; (4) removing ions by ultrafiltration; and (5) drying, crushing and packaging. In the extraction method of the present application, by using natural polymer bioflocculant chitosan, the high-viscosity fermentation broth can be processed without dilution and addition of filter aids and organic solvents for alcohol precipitation, which reduces the pressure of subsequent decolorization, properly recycles the cell proteins, and avoids the potential hazard of the organic solvents. The method can obtain high-purity pullulan polysaccharide, improving the product yield and quality, reducing solid waste, reducing the production cost, and achieving a safe, efficient, continuous and automated production process.

Abstract: The present invention belongs to the bioengineering field, and relates to a method for fermentation production of L-theanine by using an Escherichia coli genetically engineered bacterium. The engineered bacterium is obtained by serving a strain as an original strain, wherein the strain is obtained after performing a single copy of T7RNAP, a dual copy of gmas, xylR knockout, and sucCD knockout on an Escherichia coli W3110 genome, and by integrating genes xfp, pta, acs, gltA, and ppc, and knocking out ackA on the genome. The present invention has a high yield, and stable production performance; after 20-25 h, L-theanine has a titer of 75-80 g/L, and the yield is up to 52-55%. The fermentation broth is purified by membrane separation in combination with a cation-anion resin series technique. Moreover, the one-step crystallization yield is 72.3% and the L-theanine final product has a purity of 99%.

Abstract: A method for extracting pullulan polysaccharide from high-viscosity fermentation broth includes following steps: (1) removing cells from the fermentation broth; (2) removing proteins; (3) decolorizing by macroporous resin adsorption; (4) removing ions by ultrafiltration; and (5) drying, crushing and packaging. In the extraction method of the present application, by using natural polymer bioflocculant chitosan, the high-viscosity fermentation broth can be processed without dilution and addition of filter aids and organic solvents for alcohol precipitation, which reduces the pressure of subsequent decolorization, properly recycles the cell proteins, and avoids the potential hazard of the organic solvents. The method can obtain high-purity pullulan polysaccharide, improving the product yield and quality, reducing solid waste, reducing the production cost, and achieving a safe, efficient, continuous and automated production process.

Abstract: The present disclosure discloses an energy-saving method for preparing electronic-grade carbonate, including the following steps that: industrial-grade dimethyl carbonate and anhydrous ethanol enter a reaction process after being preheated by a preheater, and are subjected to an esterification reaction under the action of a catalyst to obtain a mixture containing dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate, and an azeotrope of dimethyl carbonate and methanol; the above-mentioned mixture enters a recovery process of dimethyl carbonate to recover unreacted dimethyl carbonate; a mixture of ethyl methyl carbonate and diethyl carbonate then enters a crude separation process to obtain crude ethyl methyl carbonate and crude diethyl carbonate; and the crude ethyl methyl carbonate is subjected to a refining process of ethyl methyl carbonate to obtain electronic-grade ethyl methyl carbonate, and the crude diethyl carbonate is subjected to a refining process of diethyl carbonate to obtain electronic

Abstract: The disclosure discloses a method for producing ?-calcium sulfate hemihydrate whiskers by using fermentation broth for producing lactic acid with a calcium salt method as a raw material and synchronously recovering a lactic acid monomer. The method comprises the following steps: 1) after fermentation of lactic acid is ended, heating fermentation broth; 2) stirring, and adding sulfuric acid for reaction; 3) after the reaction is ended, filtering and collecting a solid part, namely ?-calcium sulfite hemihydrate whiskers, and collecting a liquid part, namely a free lactic acid solution containing the lactic acid monomer; and 4) washing and drying the obtained ?-calcium sulfate hemihydrate whiskers to obtain a ?-calcium sulfate hemihydrate whisker finished product, filtering and concentrating the obtained free lactic acid solution to obtain a lactic acid crude product, and refining the lactic acid crude product to obtain a high-purity lactic acid monomer.

Abstract: The invention relates to a 2-isopropyl malate synthase, a genetically engineered bacterium for producing L-leucine and application thereof and belongs to the field of metabolic engineering. The genetically engineered bacterium is obtained by overexpressing an isopropyl malate synthase coding gene leuAM for relieving feedback inhibition by L-leucine, an acetohydroxy acid synthase coding gene ilvBNM for relieving feedback inhibition by L-isoleucine, a 3-isopropyl malate dehydrogenase coding gene leuB and a 3-isopropyl malate dehydratase coding gene leuCD in host cells. The genetically engineered bacterium for producing the L-leucine is free from nutritional deficiency, rapid in growth, short in fermentation period, high in yield and high in conversion rate.

Abstract: A genetically engineered strain having high-yield of L-valine is disclosed. Starting from Escherichia coli W3110, an acetolactate synthase gene alsS of Bacillus subtilis is inserted into a genome thereof and overexpressed; a ppGpp 3?-pyrophosphate hydrolase mutant R290E/K292D gene spoTM of Escherichia coli is inserted into the genome and overexpressed; a lactate dehydrogenase gene ldhA, a pyruvate formate lyase I gene pflB, and genes frdA, frdB, frdC, frdD of four subunits of fumaric acid reductase are deleted from the genome; a leucine dehydrogenase gene bcd of Bacillus subtilis replaces a branched chain amino acid transaminase gene ilvE of Escherichia coli; and an acetohydroxy acid isomeroreductase mutant L67E/R68F/K75E gene ilvCM replaces the native acetohydroxy acid isomeroreductase gene ilvC of Escherichia coli. Furthermore, the L-valine fermentation method is improved by using a two-stage dissolved oxygen control. The L-valine titer and the sugar-acid conversion rate are increased.

Abstract: The present disclosure belongs to the field of bioengineering, and relates to breeding of industrial microorganisms, in particular to a genetically engineered strain of Saccharomyces cerevisiae, method for constructing the same, and its use for brewing, the genetically engineered strain of Saccharomyces cerevisiae heterogeneously overexpresses an acetaldehyde dehydrogenase gene ALD6, an acetyl-CoA synthase gene ACS1 and an alcohol acyltransferase gene AeAT9. The Saccharomyces cerevisiae strain with high yield of ethyl acetate and low yield of higher alcohols provided by the present disclosure not only maintains excellent ethanol fermentation characteristics, but also reducing the production of higher alcohols which adversely affect the comfort after drinking, which is of great significance for a well-maintained and strengthened flavor characteristics of Chinese Baijiu, an improved and stabilized quality thereof, and even a reform in the fermentation process thereof.

Abstract: A Saccharomyces cerevisiae strain with high yield of ethyl butyrate and a construction method and an application thereof are provided. The strain is obtained by over-expressing in the starting strain acetyl coenzyme A acyl transferase gene Erg10, 3-hydroxybutyryl coenzyme A dehydrogenase gene Hbd, 3-hydroxybutyryl coenzyme A dehydratase gene Crt, trans-2-enoyl coenzyme A reductase gene Ter, and alcohol acyl transferase gene AAT. Compared to the starting bacteria not producing ethyl butyrate, the yield of ethyl butyrate of the constructed strain reaches 77.33±3.79 mg/L, the yield of the ethyl butyrate of the strain with double copy expression of gene Ter and gene AAT reaches 99.65±7.32 mg/L, increased by 28.9% compared with the EST strain, and 40.93±3.18 mg/L of ethyl crotonate is unexpectedly produced.

Abstract: A genetically engineered bacterium includes a genome of the Eschericia coli and a mutant encoding gene hisG* of a Corynebacterium glutamicum ATP phosphoribosyl transferase HisG on the genome, and the gene hisG* is strongly expressed to enhance activity of a key enzyme HisG for histidine synthesis. The gene hisG* has a nucleotide sequence as shown in SEQ ID NO: 1; a copy number of histidine operon genes hisDBCHAFI of the Eschericia coli is further increased on the genome to enhance a terminal synthetic route of histidine; an encoding gene lysE from an arginine/lysine transportprotein of the Corynebacterium glutamicum is further integrated to the genome and strongly expressed to promote the intracellular histidine secrete to the extracellular space; and an encoding gene rocG of glutamate dehydrogenase of Bacillus subtilis is further integrated to the genome and strongly expressed to promote generation of histidine.

Abstract: An alkaline protease mutant, and a gene, engineered strain, a preparation method and application thereof are provided. The method comprises the following steps of extracting genome DNA of Bacillus clausii, performing PCR amplification to obtain a wild-type alkaline protease gene sequence, mutating the wild-type alkaline protease gene obtained by the amplification through an error-prone PCR, performing high-throughput screening to obtain a plurality of highly active alkaline protease genes, performing DNA shuffling on the highly active alkaline protease genes, and performing screening to obtain eight alkaline protease mutant genes with higher activity.

Abstract: A genetically engineered strain having high-yield of L-valine is disclosed. Starting from Escherichia coli W3110, an acetolactate synthase gene alsS of Bacillus subtilis is inserted into a genome thereof and overexpressed; a ppGpp 3?-pyrophosphate hydrolase mutant R290E/K292D gene spoTM of Escherichia coli is inserted into the genome and overexpressed; a lactate dehydrogenase gene ldhA, a pyruvate formate lyase I gene pflB, and genes frdA, frdB, frdC, frdD of four subunits of fumaric acid reductase are deleted from the genome; a leucine dehydrogenase gene bcd of Bacillus subtilis replaces a branched chain amino acid transaminase gene ilvE of Escherichia coli; and an acetohydroxy acid isomeroreductase mutant L67E/R68F/K75E gene ilvCM replaces the native acetohydroxy acid isomeroreductase gene ilvC of Escherichia coli. Furthermore, the L-valine fermentation method is improved by using a two-stage dissolved oxygen control. The L-valine titer and the sugar-acid conversion rate are increased.

Abstract: An alkaline protease mutant, and a gene, engineered strain, a preparation method and application thereof are provided. The method comprises the following steps of extracting genome DNA of Bacillus clausii, performing PCR amplification to obtain a wild-type alkaline protease gene sequence, mutating the wild-type alkaline protease gene obtained by the amplification through an error-prone PCR, performing high-throughput screening to obtain a plurality of highly active alkaline protease genes, performing DNA shuffling on the highly active alkaline protease genes, and performing screening to obtain eight alkaline protease mutant genes with higher activity.

Abstract: The present invention discloses a novel nano-composite antibacterial material and a preparation method and an application thereof, and belongs to the technical field of preservative materials. The novel nano-composite antibacterial material disclosed by the present invention is prepared by mixing a dimethylimidazole solution, deionized water and a zinc nitrate solution to prepare a metal-organic framework carrier, compositing with nisin to form a nano antibacterial composite material, separating out from a solution in a precipitate form, centrifuging, removing a supernatant, cleaning and re-suspending with the deionized water. The novel nano-composite antibacterial material prepared by the present invention has an antibacterial effect superior to nisin having a same concentration.

Abstract: The present disclosure relates to the field of genetic engineering, especially relates to a xylose-induced genetically engineered bacteria used for producing ectoine as well as a construction method and use thereof. The genetically engineered bacteria is constructed by heterologously expressing the ectABC gene cluster from Halomonas elongata on the E. coli chromosome, using the promoter of xylose transporter coding gene xylF to control the RNA polymerase from T7 bacteriophage, reconstructing a synthesis pathway of ectoine and constructing a plasmid-free system, and enhancing the expression of target genes by a strong promoter T7; the yield of ectoine reached 12-16 g/L after 20-28 h fermentation in shake flask, and reached 35-50 g/L after 24-40 h fermentation in a 5 L fermentor.

Abstract: A genetically engineered bacterium includes a genome of the Eschericia coli and a mutant encoding gene hisG* of a Corynebacterium glutamicum ATP phosphoribosyl transferase HisG on the genome, and the gene hisG* is strongly expressed to enhance activity of a key enzyme HisG for histidine synthesis. The gene hisG* has a nucleotide sequence as shown in SEQ ID NO: 1; a copy number of histidine operon genes hisDBCHAFI of the Eschericia coli is further increased on the genome to enhance a terminal synthetic route of histidine; an encoding gene lysE from an arginine/lysine transportprotein of the Corynebacterium glutamicum is further integrated to the genome and strongly expressed to promote the intracellular histidine secrete to the extracellular space; and an encoding gene rocG of glutamate dehydrogenase of Bacillus subtilis is further integrated to the genome and strongly expressed to promote generation of histidine.

Abstract: The present invention belongs to the bioengineering field, and relates to a method for fermentation production of L-theanine by using an Escherichia coli genetically engineered bacterium. The engineered bacterium is obtained by serving a strain as an original strain, wherein the strain is obtained after performing a single copy of T7RNAP, a dual copy of gmas, xylR knockout, and sucCD knockout on an Escherichia coli W3110 genome, and by integrating genes xfp, pta, acs, gltA, and ppc, and knocking out ackA on the genome. The present invention has a high yield, and stable production performance; after 20-25 h, L-theanine has a titer of 75-80 g/L, and the yield is up to 52-55%. The fermentation broth is purified by membrane separation in combination with a cation-anion resin series technique. Moreover, the one-step crystallization yield is 72.3% and the L-theanine final product has a purity of 99%.

Abstract: A method of using lactase for generating galactooligosaccharide as well as the preparation and an application of the lactase are provided. Lactase (BglD305 derived from Bacillus circulans B2301 and BglD derived from Bacillus circulans ATCC 31382) molecules from two sources are taken as the basis for molecular evolution, so as to obtain new lactase enzyme molecules with high galactooligosaccharide synthesis efficiency and good expression performance. The high-producing strain lactase is further constructed, the lactase can be efficiently synthesized during the submerged fermentation, and the enzyme molecule is secreted into the culture medium, the high-activity enzyme preparation is directly prepared from the fermentation supernatant, and the lactase expression level can achieve 2208 U/mL. As the result, the fermentation manufacturing cost of lactase is reduced, the fermentation manufacturing process is simplified, and the quality of the lactase preparation is improved.

Abstract: Disclosed is a targeted delivery system for a hydrophobic antitumor drug, referring to conjugates of E-selectin polypeptide ligand-polyethylene glycol-antitumor drug connected by different link bridges containing disulfide bonds. The synthesis of the conjugates, antitumor activity evaluation, the particle size and morphology characteristics of nanoparticles self-assembled by the conjugates in an aqueous solution, and the release of the antitumor drug in different conditions are comprised. The conjugates can actively target at vessels of a tumor site by the E-selectin peptide ligand, and can also self-assemble into nanoparticles in an aqueous solution, so as to be passively targeted at the tumor site by EPR effect.