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: 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: 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: 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: A superhydrophobic polypropylene porous film, including a polypropylene porous film substrate, titanium dioxide layers and a surface modifier layer, is disclosed. The titanium dioxide layers are deposited on the surface of the polypropylene porous film substrate by atomic deposition technology; a surface modifier is coated on the titanium dioxide layers; hydrophobic bonds are formed between the titanium dioxide layers and the surface modifier layer; the superhydrophobic polypropylene porous film has a water contact angle greater than 150 degrees, a rolling angle less than 10 degrees, an aperture of 0.1-0.4 ?m, a porosity of 50%-80%, a tensile strength of 30-50 MPa, and an elongation at break of 10%-30%.

Abstract: An Aureobasidium pullulans recombinant strain with high-yield heavy oil and a construction method and application thereof are provided. The Aureobasidium pullulans recombinant strain is obtained by knocking out a pullulan synthetase PUL gene while overexpressing an ACL gene. The obtained Aureobasidium pullulans recombinant strain can significantly increase the yield of heavy oil. After 7-day fermentation with xylose as carbon source, the yield of the heavy oil of the recombinant strain reaches 19.4372 g/L, while the yield of the heavy oil of the original strain is 10.0325 g/L, i.e. the recombinant strain improves the yield by 93.74% compared with the original strain.

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: The present disclosure provides recombinant Pichia pastoris, a construction method thereof, and use thereof in the efficient preparation of 15?-D-ethylgonendione, and belongs to the technical field of fermentation engineering. In the present disclosure, with Pichia pastoris as a host, 15?-steroid hydroxylase and glucose-6-phosphate dehydrogenase (G6PD) are simultaneously induced in a manner of intracellular enzyme production for the first time, and the Pichia pastoris whole-cell induction and catalysis mode is used to achieve the conversion of D-ethylgonendione with high substrate loading and high conversion rate.

Abstract: The present disclosure relates to a genetically engineered strain with high production of uridine and its construction method and application. The strain was constructed as follows: heterologously expressing pyrimidine nucleoside operon sequence pyrBCAKDFE (SEQ ID NO:1) on the genome of E coli prompted by strong promoter Ptrc to reconstruct the pathway of uridine synthesis; overexpressing the autologous prsA gene coding PRPP synthase by integration of another copy of prsA gene promoted by strong promoter Ptrc on the genome; deficiency of uridine kinase, uridine phosphorylase, ribonucleoside hydrolase, homoserine dehydrogenase I and ornithine carbamoyltransferase. When the bacteria was used for producing uridine, 40-67 g/L uridine could be obtained in a 5 L fermentor after fermentation for 40-70 h using the technical scheme provided by the disclosure with the maximum productivity of 0.15-0.25 g uridine/g glucose and 1.

Abstract: A lignocellulose nanofibril material, a stable foam system based thereon, a preparation method and an application thereof are provided. The lignocellulosic nanofibril material includes the following components: 0.5-20 wt % of wood flour, 0.1-10 wt % of (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl, 2-25 mmol/g of an oxidant, 6-15 wt % of NaBr, and the remaining is water. The stable foam system based on the lignocellulosic nanofibril material includes: 0.1-1.0 wt % of the lignocellulosic nanofibril material, 0.2-1.0 wt % of a surfactant, 0.1-10 wt % of sodium chloride, 0.1-1.0 wt % of calcium chloride, 0.1-1.0 wt % of magnesium chloride, 0.1-1.0 wt % of sodium sulfate, and a balance of water.

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: An Aureobasidium pullulans recombinant strain with high-yield heavy oil and a construction method and application thereof are provided. The Aureobasidium pullulans recombinant strain is obtained by knocking out a pullulan synthetase PUL gene while overexpressing an ACL gene. The obtained Aureobasidium pullulans recombinant strain can significantly increase the yield of heavy oil. After 7-day fermentation with xylose as carbon source, the yield of the heavy oil of the recombinant strain reaches 19.4372 g/L, while the yield of the heavy oil of the original strain is 10.0325 g/L, i.e. the recombinant strain improves the yield by 93.74% compared with the original strain.