Abstract: The present invention provides a bacterial continuous evolution system, an orthogonal error-prone DNA polymerase, and a continuous evolution method. In the present invention, by combining an orthogonal DNA replication system and an orthogonal error-prone DNA polymerase, a continuous evolution method that includes all mutant types, enables long-DNA-fragment mutation, and is good in continuity and simple and convenient to operate is obtained. By inducing the opening and closing of DNA polymerase expression, switching between a linear plasmid error-prone mutation process and a high-fidelity replication process is realized, so as to achieve the efficient and continuous evolution of a target DNA sequence.

Abstract: The invention provides a Saccharomyces cerevisiae strain for producing a human milk lipid substitute. By integrating a heterologous lysophosphatidic acid acyltransferase into Saccharomyces cerevisiae and knocking out its own natural lysophosphatidic acid acyltransferase, the content of palmitic acid (C16:0) at Sn-2 position of triacylglycerol produced by Saccharomyces cerevisiae is increased, to synthesize a human milk lipid substitute. On this basis, a metabolic pathway related gene is knocked out, to further increase the content of human milk lipid substitute in the product. In the present invention, a human milk lipid substitute is de novo synthesized by Saccharomyces cerevisiae for the first time, in which the total fatty acid is 15% or more, and the relative content of C16:0 at Sn-2 position reaches about 60%.

Abstract: The invention provides a method for increasing the yield of 7-dehydrocholesterol in yeast by using compartmentalization. The method includes steps of: by taking yeast as a starting strain, expressing heterologous sterol delta 24-reductase and cholestenol delta-isomerase, wherein the yield of 7-DHC in Saccharomyces cerevisiae S288C is detected to be 10.15 mg/L. According to the method of the invention, partial enzymes in a 7-DHC synthesis path are positioned in compartments in Saccharomyces cerevisiae by using a peroxisome and a mitochondrial positioning tag, and a relatively independent 7-DHC synthesis path is formed. Meanwhile, the storage space of precursor substances needed by 7-DHC synthesis is increased, the feedback effect is reduced, the conversion efficiency between enzymes is improved in the same compartment, the loss of the acting substrate is reduced, and finally the yield of the 7-DHC is improved by 4 times and reaches 53.31 mg/L.

Abstract: The disclosure discloses construction of recombinant Saccharomyces cerevisiae for synthesizing carminic acid and application thereof and belongs to the technical field of genetic engineering and bioengineering. The disclosure obtains recombinant S. cerevisiae CA-B2 capable of synthesizing carminic acid by heterologously expressing cyclase Zhul, aromatase ZhuJ, OKS of Octaketide synthase 1, C-glucosyltransferase UGT2, monooxygenase aptC and 4?-phosphopantetheinyl transferase npgA in S. cerevisiae. The recombinant S. cerevisiae can be used for synthesizing carminic acid by taking self-synthesized acetyl-CoA and malonyl-CoA as a precursor. On this basis, OKS, cyclase, aromatase, C-glucosyltransferase and monooxygenase relevant to carminic acid are integrated to a high copy site, which can remarkably improve the yield of carminic acid. The yield of carminic acid can be increased to 2664.6 ?g/L by optimizing fermentation conditions, and the fermentation time is shortened significantly.

Abstract: The disclosure discloses recombinant Bacillus subtilis for synthesizing e lacto-N-neotetraose yield. The recombinant Bacillus subtilis is obtained by integrating two ?-1,4-galactotransferase genes on a genome of a host bacterium Bacillus subtilis 168?amyE:P43-lacY, P43-lgtB, PxylA-comK and exogenously expressing a ?-1,3-N-glucosaminotransferase gene. Compared with a strain before transformation, the recombinant Bacillus subtilis of the disclosure improves the yield of the synthesized lacto-N-neotetraose from 720 mg/L to 1300 mg/L, laying a foundation for further metabolic engineering transformation of Bacillus subtilis for producing the lacto-N-neotetraose.

Abstract: The present disclosure discloses a method for efficient catalytic synthesis of PAPS based on constructing an ATP regeneration system, and belongs to the technical field of bioengineering. Efficient production of PAPS is realized through microbial recombination expression and artificial construction of PAPS bifunctional synthetase. On the basis, an ATP regeneration system coupling with polyphosphate kinase from Corynebacterium glutamicum and Mycobacterium tuberculosis can be used for recovering two byproducts: pyrophosphoric acid and ADP at the same time, the equivalent conversion of a substrate and a product is realized, the PAPS generated in a catalysis system has high purity, and the sulfonic acid group donation in most sulfonic acid transfer reactions can be realized.

Abstract: The present invention provides a pyruvate-responsive biosensor and a construction method and use thereof. In the present invention, pyruvate-responsive biosensors with different dynamic ranges are successfully constructed by optimizing the PdhR binding sequence inserted on the P43 promoter and optimizing the insertion site, wherein the minimum increase in dynamic range is by 0.6 time, and the maximum increase is by 30.7 times. The pyruvate-responsive biosensors are useful in the precise control of the expression of each gene in the cell. Since pyruvate is a key metabolite of central carbon in the cells, these biosensors are capable of dynamically regulating the expression level of intracellular genes according to changes in the content of pyruvate in the cells, thereby achieving the dynamic control of intracellular metabolic flux. The pyruvate biosensor obtained in the present invention has a good specificity, and a response range to pyruvate of 10-35 nmol/g DCW.

Abstract: An autoinducer-2 (AI-2) molecular response-based starting element and an Escherichia coli (E. coli) dynamic regulation system and method constructed thereby are provided. A cell density-dependent starting element PJ23119-LsrR-PlsrA based on an AI-2 molecular response is constructed. The element can be used to self-induce the expression of dCpf1, and crRNAs of different target genes are further assembled, such that the self-inducible element can be used for dCpf1-CRP to achieve the dynamic regulation of genes in a synthesis pathway. In the present disclosure, vectors pACYDuet-PJ23119-LsrR-PlsrA-dCpf1-CRP, pRSFDuet-GFP-mCherry, and pETDuet-crRNA can be constructed to simultaneously achieve the transcriptional activation and inhibition of different genes. The construction method of recombinant E. coli in the present disclosure is simple and has promising application prospects.

Abstract: The disclosure discloses a genetically engineered strain for producing porcine myoglobin and fermentation and purification thereof, and belongs to the technical field of genetic engineering. The disclosure realizes efficient secretion and expression of porcine myoglobin by integrating the gene of porcine myoglobin in P. pastoris. On this basis, optimization of the medium and culture conditions of recombinant P. pastoris can significantly increase the titer of porcine myoglobin, so that the titer can reach 285.42 mg/L under fermenter conditions. In addition, by creatively adding different concentrations of ammonium sulfate to fermentation broth step by step, the purity of myoglobin obtained by final concentration is up to 88.0%, and the purification rate is up to 66.1%.

Abstract: The disclosure discloses construction of recombinant Saccharomyces cerevisiae for synthesizing carminic acid and application thereof and belongs to the technical field of genetic engineering and bioengineering. The disclosure obtains recombinant S. cerevisiae CA-B2 capable of synthesizing carminic acid by heterologously expressing cyclase Zhul, aromatase ZhuJ, OKS of Octaketide synthase 1, C-glucosyltransferase UGT2, monooxygenase aptC and 4?-phosphopantetheinyl transferase npgA in S. cerevisiae. The recombinant S. cerevisiae can be used for synthesizing carminic acid by taking self-synthesized acetyl-CoA and malonyl-CoA as a precursor. On this basis, OKS, cyclase, aromatase, C-glucosyltransferase and monooxygenase relevant to carminic acid are integrated to a high copy site, which can remarkably improve the yield of carminic acid. The yield of carminic acid can be increased to 2664.6 µg/L by optimizing fermentation conditions, and the fermentation time is shortened significantly.

Abstract: The present invention provides an acid-tolerant Saccharomyces cerevisiae strain and use thereof. By using exogenously added malic acid as a stress, an acid-tolerant mutant S. cerevisiae strain MTPfo-4 is obtained by directed evolution screening in the laboratory, which tolerates a minimum pH of 2.44. The mutant strain MTPfo-4, tolerant to multiple organic acids, has an increased tolerance to exogenous malic acid of up to 86.6 g/L. The mutant strain MTPfo-4 obtained is further identified. The mutant strain grows stably and well, and can tolerate a variety of organic acids (lactic acid, malic acid, succinic acid, fumaric acid, citric acid, gluconic acid, and tartaric acid). It also has a strong tolerance to inorganic acids (HCl and H3PO4). This is difficult to achieve in the existing research and reports of S. cerevisiae. The strain is intended to be used as an acid-tolerant chassis cell factory for producing various short-chain organic acids.

Abstract: The disclosure discloses Bacillus subtilis for producing N-acetylneuraminic acid and application thereof, and belongs to the field of genetic engineering. The disclosure optimizes the expression levels of key enzymes in N-acetylneuraminic acid synthesis pathways on genome through promoters of different strength, reduces the protein synthesis pressure caused by the expression of enzymes on cells, and further integrates the three N-acetylneuraminic acids in a same Bacillus subtilis engineering strain. Bacillus subtilis with improved N-acetylneuraminic acid production is obtained, and the production reaches 10.4 g/L at the shake flask level, laying a foundation for further improving the NeuAc production from Bacillus subtilis.

Abstract: The present disclosure discloses recombinant Escherichia coli and application thereof in screening erythritol-producing strains, and belongs to the technical field of microorganisms. The recombinant Escherichia coli used in a method for screening an erythritol-producing strain disclosed by the present disclosure can well perform positive correlation induction on erythritol with different concentrations, so that the method for screening the erythritol-producing strain has the advantage of high sensitivity.

Abstract: The disclosure discloses recombinant Bacillus subtilis for synthesizing guanosine diphosphate fucose and a construction method and application thereof. The recombinant Bacillus subtilis is obtained by intensively expressing guanylate kinase and nucleotide diphosphokinase genes and expressing exogenous fucokinase and phosphate guanylyltransferase genes in a genome of Bacillus subtilis 168. According to the disclosure, a bacterial strain for synthesizing the guanosine diphosphate fucose is obtained by reconstructing the Bacillus subtilis 168, with a volume of intracellular accumulation up to 196.15 g/L. According to the disclosure, by intensively expressing the guanylate kinase and nucleotide diphosphokinase genes, and enhancing the supply of intracellular GDP-L-fucose composition cofactors, the synthesis of the guanosine diphosphate fucose is promoted. The construction method for the recombinant Bacillus subtilis of the disclosure is simple and convenient to use, thus having good application prospects.

Abstract: The invention discloses a recombinant Corynebacterium glutamicum for efficient synthesis of highly pure hyaluronic acid and oligosaccharides thereof, belonging to the technical field of bioengineering. The recombinant Corynebacterium glutamicum constructed in the present invention can produce hyaluronic acid with a yield up to 40g/L, and a crude product purity of 95%. Addition of exogenous hyaluronic acid hydrolase and optimization of the fermentation conditions results in hyaluronic acid oligosaccharides with specific molecular weight, and can further improve the yield of hyaluronic acid to 72 g/L. The invention lays a solid foundation for the efficient synthesis of highly pure hyaluronic acid by microorganisms, and the constructed recombinant Corynebacterium glutamicum is suitable for industrial production and application.

Abstract: The present invention provides a recombinant Corynebacterium glutamicum producing N-acetylglucosamine and use thereof. The recombinant Corynebacterium glutamicum is obtained by overexpressing, in Corynebacterium glutamicum, the transcription factor SugR derived therefrom. The recombinant Corynebacterium glutamicum of the present invention increases the production of acetylglucosamine to up to 26 g/L, and lays a foundation for further metabolic engineering of Corynebacterium glutamicum to produce glucosamine.

Abstract: The disclosure discloses a genetically engineered strain for producing porcine myoglobin and fermentation and purification thereof, and belongs to the technical field of genetic engineering. The disclosure realizes efficient secretion and expression of porcine myoglobin by integrating the gene of porcine myoglobin in P. pastoris. On this basis, optimization of the medium and culture conditions of recombinant P. pastoris can significantly increase the titer of porcine myoglobin, so that the titer can reach 285.42 mg/L under fermenter conditions. In addition, by creatively adding different concentrations of ammonium sulfate to fermentation broth step by step, the purity of myoglobin obtained by final concentration is up to 88.0%, and the purification rate is up to 66.1%.

Abstract: The disclosure discloses a recombinant Bacillus subtilis engineered bacterium capable of efficiently expressing keratinase, and belongs to the technical fields of genetic engineering and fermentation engineering. The disclosure successfully constructs a genetically engineered bacterium B. subtilis WB600-pP43NMK-ker capable of efficiently expressing keratinase by using a keratinase gene from Bacillus licheniformis (BBE11-1) as a target gene, pP43NMK as an expression vector and B. subtilis WB600 as an expression host; and meanwhile, the disclosure conducts in-depth research on fermentation media and fermentation conditions when the engineered bacteria are configured as a production strain to produce keratinase to obtain a fermentation medium capable of increasing a yield of keratinase and an optimum process for fermentation production of keratinase.

Abstract: The present disclosure discloses a visualized screening method for an Aspergillus recombinant strain with multigene editing and belongs to the technical field of gene engineering. CRISPR-Cas9 is used in the disclosure to cleave spore color change-related genes and a target gene in Aspergillus at the same time, such that editing of the target gene is visualized and an Aspergillus niger strain with multigene editing can be rapidly and efficiently screened out through spore phenotypes. Through different combinations of visualized genes and non-phenotypic change genes, rapid screening of the strain with multigene editing and simultaneous screening of multiple visualized genes are realized, and use of resistance genes in industrial strains is reduced.

Abstract: The present invention discloses a RamA transcription factor mutant for promoting the production of N-acetylglucosamine and use thereof. The mutant is obtained by mutating lysine at position 90 to asparagine and serine at position 92 to lysine in a parent having an amino acid sequence as shown in SEQ ID NO: 2. The present invention provides a genetically engineered strain that overexpresses the RamA transcription factor mutant and increases the production of N-acetylglucosamine. By overexpressing the transcription factor RamA that is involved in the regulation of carbon metabolism, the extracellular accumulation of N-acetylglucosamine is increased, with a maximum concentration reaching 31.5 g/L, which lays a foundation for further metabolic engineering of Corynebacterium glutamicum to produce glucosamine. The method for constructing recombinant Corynebacterium glutamicum of the invention is simple, and convenient in use, and thus has good application prospects.