Abstract: The invention belongs to the field of cosmetic biotechnology, and specifically relates to an Enterobacter that degrades hyaluronic acid and a cultivation method and application thereof. The Enterobacter sp. CGJ001 of the present invention was deposited in the China General Microbiological Culture Collection Center on Oct. 10, 2019, and the preservation number is CGMCC NO. 18661. The Enterobacter strain can efficiently produce hyaluronidase, and can be used in the process of preparing low molecular hyaluronic acid and oligomeric hyaluronic acid from high molecular hyaluronic acid. The enzyme has high specificity towards hyaluronic acid, excellent thermal stability and pH stability, and is suitable for large-scale industrial application. Thus, it can replace the traditional hyaluronidase extracted from expensive animal tissues. There should be broad application prospects in the fields of medicine and cosmetics.

Abstract: The invention belongs to the field of cosmetic biotechnology, and specifically relates to an Enterobacter that degrades hyaluronic acid and a cultivation method and application thereof. The Enterobacter sp. CGJ001 of the present invention was deposited in the China General Microbiological Culture Collection Center on Oct. 10, 2019, and the preservation number is CGMCC NO. 18661. The Enterobacter strain can efficiently produce hyaluronidase, and can be used in the process of preparing low molecular hyaluronic acid and oligomeric hyaluronic acid from high molecular hyaluronic acid. The enzyme has high specificity towards hyaluronic acid, excellent thermal stability and pH stability, and is suitable for large-scale industrial application. Thus, it can replace the traditional hyaluronidase extracted from expensive animal tissues. There should be broad application prospects in the fields of medicine and cosmetics.

Abstract: The present invention provides a phospholipase D having an amino acid sequence as shown in SEQ ID NO. 1, and further provides a gene sequence encoding phospholipase D, which has a nucleotide sequence as shown in SEQ ID NO. 2. The present invention also provides a method for improving the expression level of phospholipase D by systematically engineering the expression elements. The method comprises screening and replacement of signal peptides, ribosome binding sites and promoters. The constructed recombinant plasmid is transformed into a host cell, and the recombinant strain is capable of successfully expressing phospholipase D. The phospholipase D of the present invention has a good phosphatidyl transferring ability, and can be used for synthesizing the product phosphatidylserine with lecithin and L-serine as substrates. The recombinant strain has good stability of enzyme activity and short fermentation period, which lays the foundation for large-scale industrial production.

Abstract: The invention belongs to the field of cosmetic biotechnology, and specifically relates to an Enterobacter that degrades hyaluronic acid and a cultivation method and application thereof. The Enterobacter sp. CGJ001 of the present invention was deposited in the China General Microbiological Culture Collection Center on Oct. 10, 2019, and the preservation number is CGMCC NO. 18661. The Enterobacter strain can efficiently produce hyaluronidase, and can be used in the process of preparing low molecular hyaluronic acid and oligomeric hyaluronic acid from high molecular hyaluronic acid. The enzyme has high specificity towards hyaluronic acid, excellent thermal stability and pH stability, and is suitable for large-scale industrial application. Thus it can replace the traditional hyaluronidase extracted from expensive animal tissues. There should be broad application prospects in the fields of medicine and cosmetics.

Abstract: The invention relates to the technical field of industrial biotechnologies, and discloses a keratinase mutant with improved thermal stability and use thereof. The asparagine at position 181, the tyrosine at position 217, and the serine at position 236 in the keratinase derived from Brevibacillus parabrevis (CGMCC No. 10798) are engineered by site-direction mutation, and combined at random to obtain an enzyme with combined mutations. The invention realizes the remarkable improvement of the thermal stability of keratinase, and has good theoretical value and application prospect.

Abstract: The present invention provides a phospholipase D having an amino acid sequence as shown in SEQ ID NO. 1, and further provides a gene sequence encoding phospholipase D, which has a nucleotide sequence as shown in SEQ ID NO. 2. The present invention also provides a method for improving the expression level of phospholipase D by systematically engineering the expression elements. The method comprises screening and replacement of signal peptides, ribosome binding sites and promoters. The constructed recombinant plasmid is transformed into a host cell, and the recombinant strain is capable of successfully expressing phospholipase D. The phospholipase D of the present invention has a good phosphatidyl transferring ability, and can be used for synthesizing the product phosphatidylserine with lecithin and L-serine as substrates. The recombinant strain has good stability of enzyme activity and short fermentation period, which lays the foundation for large-scale industrial production.

Abstract: The invention relates to the technical field of industrial biotechnologies, and discloses a keratinase mutant with improved thermal stability and use thereof. The asparagine at position 181, the tyrosine at position 218, and the serine at position 236 in the keratinase derived from Brevibacillus parabrevis (CGMCC No. 10798) are engineered by site-direction mutation, and combined at random to obtain an enzyme with combined mutations. The invention realizes the remarkable improvement of the thermal stability of keratinase, and has good theoretical value and application prospect.

Abstract: The present invention discloses a directionally modified glucosamine synthase mutant and its application. The amino acid sequence of the glucosamine synthase mutant is as shown in sequence list SEQ ID No. 1, and the nucleotide sequence is as shown in sequence list SEQ ID No. 2. The genetic engineering bacteria of glucosamine synthase is successfully constructed. In order to improve the tolerance of recombinant bacteria against glucosamine, the glucosamine synthase is directionally modified. A glucosamine synthase mutant is selected from the mutant library via high-throughput screening method, the amino acid changes in the mutant induces the spatial conformational change in the enzyme, so as enlarged the region where the enzyme and substrate combines, therefor the combination efficiency of the enzyme and the substrate is increased. The glucosamine synthase of the present invention has various advantages, such as rich in raw material of glucose, and a convenient subsequent extraction.

Abstract: The present invention discloses a directionally modified glucosamine synthase mutant and its application. The amino acid sequence of the glucosamine synthase mutant is as shown in sequence list SEQ ID No. 1, and the nucleotide sequence is as shown in sequence list SEQ ID No. 2. The genetic engineering bacteria of glucosamine synthase is successfully constructed. In order to improve the tolerance of recombinant bacteria against glucosamine, the glucosamine synthase is directionally modified. A glucosamine synthase mutant is selected from the mutant library via high-throughput screening method, the amino acid changes in the mutant induces the spatial conformational change in the enzyme, so as enlarged the region where the enzyme and substrate combines, therefor the combination efficiency of the enzyme and the substrate is increased. The glucosamine synthase of the present invention has various advantages, such as rich in raw material of glucose, and a convenient subsequent extraction.