559 results about "E coli bacteria" patented technology

The invention belongs to the technical field of microorganisms, and particularly relates to recombinant escherichia coli containing a PDRN sequence and a preparation method thereof, and the preparation method comprises the following steps: S1, preparing a PDRN solution; s2, complementing the double strands of the PDRN into blunt ends; s3, constructing a recombinant plasmid; s4, carrying out mixed culture on a product obtained in the step S3 and escherichia coli DH5alpha; s5, screening the recombinants; s6, carrying out PCR (Polymerase Chain Reaction) amplification, and recording a strain from a fragment with the length of more than 200bp; s7, preparing a seed solution by adopting the strain prepared in the step S6; s8, strain fermentation; and S9, centrifugally collecting thalli. The method comprises the following steps: constructing a recombinant plasmid containing a PDRN fragment, introducing the recombinant plasmid into Escherichia coli, subsequently culturing the recombinant Escherichia coli to copy DNA in the Escherichia coli, extracting a purified exogenous gene fragment to obtain a strain containing a single fragment PDRN sequence, and getting rid of dependence on raw materials during subsequent extraction.

The invention provides antibacterial ceramic and a preparation method thereof. The antibacterial ceramic comprises a blank body and a glaze layer, the blank body is prepared from the following raw materials: kaolin, diatomite, montmorillonite, soapstone, bamboo charcoal powder, a first antibacterial agent, a fluxing agent, a pore forming agent, an adhesive and a reinforcing agent; the glaze layer comprises the following raw materials: kaolin, diatomite, dolomite, tourmaline, sodium oxide, a second antibacterial agent, a binder, a stabilizer and a dispersant. The method comprises the following steps: firing a molded green body by adopting stepped segmented heating, and carrying out glaze firing by adopting stepped segmented heating after glazing, thereby obtaining the antibacterial ceramic. According to the antibacterial ceramic disclosed by the invention, the antibacterial agent is added into the green body and the glaze layer, so that the influence on the antibacterial property of the green body in the firing process of the green body is avoided, the antibacterial durability is further improved, the antibacterial effect is enhanced, and the antibacterial rate on pathogenic bacteria such as escherichia coli and staphylococcus aureus reaches 99.99%.

The invention relates to methods and compositions for treating or preventing an infection by E coli cells in human or animal subjects. The method comprises administering to the subject a plurality of transduction particles that encode a nuclease for targeting the genomes of B2 phylogroup E coli cells.

The invention provides copper-loaded duck-origin lactobacillus plantarum with high antibacterial peptide yield and application of the copper-loaded duck-origin lactobacillus plantarum. The preservation number of the provided copper-loaded duck-origin lactobacillus plantarum is CGMCC (China General Microbiological Culture Collection Center) NO.32835. The domesticated and bred duck-origin lactobacillus plantarum with high antibacterial peptide yield can tolerate high-concentration copper ions, the domesticated and bred lactobacillus plantarum can stably grow, and the contents of antibacterial peptide, extracellular protein, lipase, amylase, lactic acid, acetic acid and the like in the domesticated and bred lactobacillus plantarum strain are increased; and the amino acid composition is changed. The strain can convert inorganic copper into organic copper, the utilization rate of copper is increased, and growth and development of organisms are promoted. Moreover, small peptides and extracellular proteins in metabiotics generated after fermentation have the effect of effectively inhibiting harmful bacteria such as riemerella anatipestifer, escherichia coli, salmonella and staphylococcus of poultry, and are beneficial to eliminating intestinal inflammatory factors, maintaining intestinal health and improving the feed utilization rate.

The invention discloses a method for regulating the transport activity of a strain to 1-aminocyclopropane-1-carboxylic acid, and relates to the technical field of bioengineering. The method for regulating and controlling the transport activity of the strain to 1-aminocyclopropane-1-carboxylic acid and / or methionine analogues and the tolerance of the strain to the 1-aminocyclopropane-1-carboxylic acid and / or methionine analogues, disclosed by the invention, comprises the step of transferring a LeuE gene into escherichia coli to obtain an escherichia coli recombinant strain with corresponding functions. The invention discloses the application of the LeuE protein and the LeuE gene in regulating and controlling the transport activity of escherichia coli to the 1-aminocyclopropane-1-carboxylic acid and / or methionine analogue and the tolerance of escherichia coli to the 1-aminocyclopropane-1-carboxylic acid and / or methionine analogue for the first time. The invention discloses that LeuE is an optimal candidate gene for constructing ACC synthetic bacteria for the first time, and the substrate specific transport of the LeuE meets the aim of enhancing the ACC tolerance of cells without influencing precursor supply.

The invention provides a method for constitutive expression of foreign protein by escherichia coli Nissle 1917, and belongs to the technical field of genetically engineered bacteria. The invention provides a method for constitutive expression of foreign protein by Escherichia coli Nissle 1917 (EcN), which is characterized in that EcN is used as a chassis strain, an engineering strain for constitutive expression of the foreign protein is constructed by transforming a covert plasmid, and high-efficiency expression of the foreign protein can be realized without induction of an inducer and antibiotic pressure. By utilizing the method disclosed by the invention, the EcN engineering bacterium for constitutive expression of the foreign protein RtSOD is successfully constructed, constitutive efficient expression of the high-stability RtSOD protein in the EcN engineering bacterium can be realized without using antibiotic pressure and inducer induction, and the EcN engineering bacterium can be used as a potential viable bacterium medicine for preventing and treating oxidative stress related diseases and has a wide application prospect. And the method has important significance on the practical application of the EcN engineering strain.

The invention discloses recombinant escherichia coli for producing heme and derivative compounds thereof and a preparation method of the recombinant escherichia coli. According to the invention, on the basis of escherichia coli, ptsG, galR, lpxM, pta, poxB, arcA, ldhA, sdhA, iclR, metA and dapD are knocked out; the method comprises the following steps: introducing glk, Zglf, acs, ppc, BsmetA, BsyjcI, BsdapH, BspatA and BscdapL, and enhancing the expression of araE, stA, coA, serA and gltA; and the expression of icd is weakened. And the expression of eamA and rhtA is enhanced. The GYDH and the hemA are introduced; according to the recombinant strain, D-glucose is used as a raw material to synthesize 5-ALA, and on the basis of the 5-ALA, coding genes of the heme and the various derivative compounds thereof are introduced, so that recombinant bacteria for producing the heme and the various derivative compounds thereof can be obtained.

The invention relates to the technical field of microorganisms, in particular to a bacteriophage capable of splitting a high-risk escherichia coli clone strain and targeting multiple serotypes and application of the bacteriophage. The invention discloses a bacteriophage capable of splitting a high-risk escherichia coli clone strain and targeting multiple serotypes, the bacteriophage is named as Escherichia phage vBEcoM32M3Y, the bacteriophage is preserved in the China General Microbiological Culture Collection Center (CGMCC), and the preservation number is CGMCC No.45969. The invention further discloses a preparation method of the bacteriophage. The bacteriophage disclosed by the invention is low in MOI, good in stability, good in cracking activity, free of drug-resistant and virulence genes in a genome sequence, and relatively good in clinical application value.

The invention provides recombinant escherichia coli for producing chondroitin sulfate A and application of the recombinant escherichia coli, and relates to the technical field of genetic engineering. According to the recombinant escherichia coli disclosed by the invention, chondroitin synthase, chondroitin 4-O-sulfotransferase, N-acetyl glucosamine epimerase, UDP-glucose dehydrogenase and chondroitin sulfate degrading enzyme are overexpressed; wherein the amino acid sequence of the chondroitin sulfate degrading enzyme is as shown in SEQ ID NO. 5. The recombinant escherichia coli is inoculated into a culture medium for fermentation culture, the average molecular weight of the obtained chondroitin sulfate A is 800Da, and the yield is about 12.5 g / L. Therefore, low-molecular-weight chondroitin sulfate A can be obtained and the yield of chondroitin sulfate A can be increased by fermenting the recombinant escherichia coli disclosed by the invention.

The invention relates to the technical field of polyether-ether-ketone composite materials, in particular to a conjugated polythiophene-polyether-ether-ketone-based high-antibacterial coating and a preparation method thereof.The preparation method comprises the steps that hydroxyl modified boron nitride with photocatalytic capacity and aminated PEEK are subjected to melt blending to generate chemical bonding, and a BN-OH / PEEK-NH2 composite fine powder material is formed; then carrying out oxidative polymerization on the BN-OH / PEEK-NH2 composite fine powder and a thiophene monomer under the action of an oxidizing agent, carrying out in-situ synthesis to obtain a polythiophene / BN-OH / PEEK-NH2 conjugated composite material, and subsequently spraying the polythiophene / BN-OH / PEEK-NH2 conjugated composite material to the surface of a base material to prepare a composite coating with excellent antibacterial property, high thermal stability and low friction coefficient; the antibacterial rate of the coating on escherichia coli and staphylococcus aureus under illumination reaches 90% or above, and the coating is suitable for the medical antibacterial field.

The invention provides an alpha-glucosidase mutant and application thereof in synthesis of alpha-arbutin, and the alpha-glucosidase mutant comprises the following steps: maltose and hydroquinone are taken as substrates, the recombinant bacteria are taken as a catalyst, catalytic reaction is carried out under a heating condition, and the alpha-arbutin is obtained. According to the synthesis method, maltose and hydroquinone are used as reaction substrates, and alpha-arbutin is generated through whole-cell catalysis; meanwhile, the sequence of the alpha-glucosidase mutant is integrated onto a pRSEDuet-1 expression vector and transferred into escherichia coli BL21 (DE3) for expression, a reaction system of recombinant bacteria is optimized, the optimal catalytic condition is determined, the yield of alpha-arbutin under the optimal condition is 24.8 g / L, the yield can reach 95.6% and is improved by 1.2 times compared with that of an original strain, and the alpha-glucosidase mutant has a good application prospect.

The invention discloses a genetically engineered bacterium for producing tanshinol as well as a construction method and application of the genetically engineered bacterium, and the construction method comprises the following steps: (1) taking escherichia coli W3110 as an original strain, and reconstructing a tanshinol synthesis route in cytoplasm; (2) positioning flavin reductase from klebsiella pneumoniae and a 4-hydroxyphenylacetic acid-3 hydroxylase mutant in a periplasmic space by using periplasmic space positioning signal peptide sufI. The genetically engineered bacterium for producing the tanshinol disclosed by the invention has the advantages that the yield of the tanshinol reaches 2.8 g / L after being subjected to shake flask fermentation for 24 hours, and the yield of the tanshinol reaches 26.6 g / L after being fermented in a 5L fermentation tank for 48 hours.

The invention relates to the field of genetic engineering, in particular to a genetically engineered bacterium for efficiently synthesizing 5-aminolevulinic acid. According to the invention, a synthetic biological technology and a genetic engineering means are utilized, escherichia coli E.coli BL21 (DE3) is taken as an original strain, a C5 way of the escherichia coli E.coli BL21 (DE3) is modified, and degradation of glutamic acid is reduced by knocking out a gadA gene and replacing a promoter of an argE gene; the synthesis of the 5-aminolevulinic acid is increased by enhancing the expression of gdhA, hemAS and hemL genes, replacing promoters and increasing the carbon flux flowing to the 5-aminolevulinic acid; in addition, by knocking out acetic acid synthesis genes ackA, poxB and pta, the loss of carbon flux flowing to TCA circulation is reduced, so that the purpose of increasing the yield of 5-aminolevulinic acid is achieved.

The invention discloses prokaryotic expression and purification of Echinococcus multilocularis glutathione S-transferase, and preparation and application of a polyclonal antibody, and relates to the technical field of biology.The technical key point is that the preparation method of the polyclonal antibody of the Echinococcus multilocularis glutathione S-transferase comprises the following steps that S1, RNA in vesicle tissue of Echinococcus multilocularis is extracted, and cDNA is prepared; s2, carrying out PCR (Polymerase Chain Reaction) amplification by taking the cDNA as a template to obtain an EmGST gene which can encode an amino acid sequence as shown in SEQ ID NO: 1; s3, connecting the EmGST gene to a prokaryotic expression vector plasmid through a double digestion enzyme reaction to construct a recombinant vector, then transfecting the recombinant vector to competent escherichia coli, and inducing prokaryotic expression and purification to obtain a recombinant protein; and S4, immunizing a mouse to prepare antiserum by taking the echinococcosis multilocularis glutathione transferase as an antigen, and purifying the antiserum to obtain the polyclonal antibody of the echinococcosis multilocularis glutathione transferase. The ImGST protein polyclonal antibody prepared by the invention has the advantages of high titer and good specificity.

The invention relates to the technical field of gene engineering, in particular to an L-rhamnose isomerase mutant, a recombinant plasmid, a mutant strain and application. The amino acid sequence of the mutant is as shown in SEQ ID NO.4, and the nucleotide sequence of the coding gene is as shown in SEQ ID NO.3. A specific mutant gene sequence is designed, a recombinant plasmid pET28a (+)-L-Rhi is successfully constructed, the gene sequence is connected between enzyme cutting sites BamH I and Hind III of an escherichia coli expression vector pET-28a (+) to construct a mutant expression vector (the recombinant plasmid pET-28a (+)-L-Rhi), the mutant expression vector is transformed into an escherichia coli BL21 competent cell, a mutant strain is obtained, and the recombinant plasmid pET-28a (+)-L-Rhi is obtained. The obtained mutant strain can overexpress L-rhamnose isomerase, the conversion rate of D-allose is remarkably improved, the thermal stability of the enzyme is remarkably improved through the design of mutation sites, and the half-life period is effectively prolonged.

The present disclosure relates to recombinant microorganisms, such as bacteria, e.g., E. coli, engineered to have improved flux and / or yield of the DXP pathway. Cells can be engineered to comprise nucleotide sequences comprising dxs polypeptides (EC 2.2.1.7); dxr polypeptides (EC 1.1.1.267); ispD polypeptides (EC 2.7.7.60); ispE polypeptides (EC 2.7.1.148); ispF polypeptides (EC 4.6.1.12); ispG polypeptides (EC 1.17.7.1 or EC 1.17.7.3); ispH polypeptides (EC 1.17.7.4); and idi polypeptides (EC 5.3.3.2). Cells can be further engineered to express redox polypeptides, e.g., ferredoxins, flavodoxins, and / or flavodoxin / ferredoxin--NADP reductases (EC 1.19.1.1 or EC 1.18.1.2), e.g., to increase the activity of the ispG and / or ispH polypeptides. Some or all of the nucleotide sequences can be heterologous to the cells. The recombinant microorganisms can be used in methods of isoprenoid production.

Compositions of bacterial tyrosyl-tRNA synthetase mutants that enable site-specific incorporation of numerous unnatural amino acids into proteins expressed in eukaryotic cells or in engineered ATM E. coli and methods of use are described. Compositions of novel unnatural amino acids that can be incorporated using these mutant bacterial tyrosyl-tRNA synthetase are also described.

The present invention belongs to the field of genetic engineering technology and discloses a plasmid-free genetically engineered bacterium that can efficiently synthesize γ-aminobutyric acid from scratch using a cheap carbon source as a substrate, a method and an application thereof. The engineered bacterium is based on wild-type E. coli MG1655, overexpresses the T7 RNA polymerase gene; deletes the genes gabT and puuE; overexpresses gadC and gad bm , gdh, gltA, pyc, and ppc genes; and a growth-coupled promoter was used to dynamically regulate the expression of the sucA and argA genes in the GABA production pathway in Escherichia coli. All genetic manipulations in this engineered bacterium were performed within the genome, leaving no plasmid residues and requiring no antibiotics or inducers. The resulting strain exhibited stable production performance and a simple fermentation process. Using the engineered bacterium under a staged pH control process for 38 hours, the yield of γ-aminobutyric acid reached 35.4 g / L, demonstrating promising industrial application potential.

The invention relates to a porcine reproductive and respiratory syndrome virus (PRRSV) dimer nucleocapsid (N) protein (PRRSV N-dimer) and application thereof. The PRRSV N-dimer is formed by connecting N protein amino acid sequences in series through (GGGGS) 3linker. According to the invention, a GGGGS 3linker nucleotide sequence is connected in series with a PRRSV NADC30-like strain N protein gene sequence to construct a prokaryotic expression vector, and a recombinant PRRSV N-dimer is expressed in escherichia coli. Through SDS-PAGE (Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis) and Western-blot detection, the recombinant PRRSV N-dimer obtains soluble expression and can be subjected to a specific reaction with PRRSV positive serum; through detection by a freeze thawing method and an ELISA (Enzyme-Linked Immunosorbent Assay) method, compared with a PRRSV monomer N protein (PRRSV N-monomer), the PRRSV N-dimer protein can be stably preserved, and the immunoreactivity is better. A PRRSV antibody indirect enzyme-linked immunosorbent assay (iELISA) detection method is established on the basis of a PRRSV N-dimer, and can be applied to diagnosis and monitoring of PRRSV infection.

The invention provides a method for efficiently expressing amidase and application of the amidase, and belongs to the technical field of enzyme technology and gene engineering. The method comprises the following steps: A1, cloning a fusion tag coding sequence for enhancing amidase expression into an escherichia coli expression vector to obtain a first recombinant expression vector; a2, cloning an amidase coding sequence into a first recombinant expression vector to construct a second recombinant expression vector, wherein amidase and the fusion tag are subjected to fusion expression, and the amidase is located at the downstream of the fusion tag; a3, introducing the second recombinant expression vector into escherichia coli competent cells to construct recombinant genetic engineering bacteria; and A4, fermenting the obtained recombinant genetically engineered bacterium to express amidase. According to the method disclosed by the invention, the expression quantity of amidase is remarkably improved by utilizing the fusion tag, chiral alkylaniline with high optical purity can be generated by utilizing the prepared amidase, and the e.e. Value of the obtained compound is greater than 97%.

The invention belongs to the technical field of microbial engineering and genetic engineering, and discloses escherichia coli for producing histidine as well as a construction method and application thereof. The escherichia coli contains a growth dependent promoter PprpB of a methyl isocitrate lyase gene prpB and / or a stable phase dependent promoter PydgI of an ornithine reverse transport protein / lysine permease gene ydgI. Escherichia coli for producing histidine uses growth dependent promoter PprpB of methylisocitrate lyase gene prpB to regulate expression of glutamine phosphoribose pyrophosphate transamidase gene purF and uses ornithine reverse transport protein / lysine permease gene (ydgI) The stable-phase dependent promoter PydgI regulates the expression of the ATP phosphoribosyltransferase gene hisG, so that the energy supply of thalli in early-stage cell growth and the metabolic flux of L-histidine in later-stage thalli production can be realized, and the balanced distribution of the metabolic flux between the cell growth of a microbial cell factory and the production of L-histidine is effectively balanced.

The invention relates to the technical field of molecular biology and protein engineering, in particular to a lactic acid bacteria antibacterial peptide LABA4 multi-copy expression method and application. The invention aims to provide a prokaryotic expression method of an antibacterial peptide LAB4 tandem gene based on a self-assembled peptide and application, so that the problems of toxicity to a host, low expression quantity and non-ideal product activity in a large intestine expression system are solved, the antibacterial peptide is efficiently expressed in escherichia coli, and the antibacterial activity is effectively improved. Particularly, the characteristics of specific cutting and no amino acid residue of enterokinase are utilized, modified recombinant enterokinase is added between LAB4 monomers to serve as an interval restriction enzyme cutting site, a gene shuffling technology is utilized to design and construct three-six copy tandem recombinant plasmids of LAB4, the self-cleavage characteristic of intein is utilized, and the recombinant enterokinase recombinant plasmids of LAB4 can be used for preparing the recombinant enterokinase recombinant plasmids of LAB4, so that the recombinant enterokinase recombinant plasmids of LAB4 can be used for preparing the recombinant enterokinase recombinant plasmids of LAB4. An optimized cspA cold shock promoter in a pCold I vector is adopted, and high-efficiency expression of tandem LAB4 in an escherichia coli expression system is realized through 15 DEG C low-temperature induction precise regulation and control.

A composition of bacteriophages comprising at least one phage selected from AHP, AHC, AKA, MIA, MP1, and MP2, wherein the phages are optionally encapsulated; and a method for preventing or treating an infection or a disease caused by avian pathogenic E. coli by administering to a subject a prophylactically or therapeutically effective amount of the composition.

The invention relates to a preparation method and application of recombinant canine lactoferrin and peptide thereof, aiming at codon preference of host cells, canine lactoferrin genes are optimized, the full length of canine lactoferrin and the lactoferrin peptide are successfully expressed by virtue of an escherichia coli expression system, and the recombinant canine lactoferrin and the peptide thereof are identified by virtue of a minimum inhibitory concentration experiment. It is proved that the canine lactoferrin and the peptide thereof have the inhibiting capacity on pathogenic bacteria such as staphylococcus aureus, salmonella typhimurium and staphylococcus pseudointermedius, and the antibacterial activity MIC of the canine lactoferrin on the staphylococcus aureus, the salmonella typhimurium and the staphylococcus pseudointermedius is 1.5 mg / mL; the antibacterial activity MIC of the dog lactoferrin peptide to staphylococcus aureus is equal to 0.75 mg / mL, and the dog lactoferrin peptide shows high antibacterial ability.

Escherichia coli is modified by means of metabolic engineering, a genetically engineered bacterium for high yield of O-succinyl-L-homoserine is obtained, and a construction method of the genetically engineered bacterium comprises the following steps: weakening a synthetic route of an organic acid metabolic byproduct of a chassis strain E.coli W3110 [delta] metI [delta] metJ [delta] thrB [delta] metB; wherein the synthetic route of the organic acid metabolic byproducts is selected from at least one of a formic acid synthetic route, a lactic acid synthetic route and an ethanol synthetic route. The constructed genetically engineered bacterium is applied to microbial fermentation production of the O-succinyl-L-homoserine, effective accumulation of the O-succinyl-L-homoserine is achieved, the sugar acid conversion rate reaches 46.8%, and a foundation is laid for subsequent construction of high-yield O-succinyl-L-homoserine engineering bacteria.

The present invention belongs to the field of cellulose synthesis, and specifically relates to a heterologous expression Escherichia coli biosynthesis system of cellulose synthase subunits PtCesA1 and PtCesA8 and its application, including a heterologous expression vector of cellulose synthase subunit PtCesA1 or a heterologous expression vector of cellulose synthase subunit PtCesA8; and a heterologous cell containing the above vector. PtCesA1 and PtCesA8 are expressed in heterologous cells respectively to form cellulose synthase, which is used to catalyze the synthesis of cellulose microfibrils. The present invention realizes the biosynthesis of cellulose in vivo, and directly synthesizes a cellulose product with high purity similar to plants and free of lignin and hemicellulose from the bacteria by heterologously expressing plant cellulose synthase subunits in Escherichia coli.

The invention provides a method for evaluating the endotoxin adsorption performance of a hemoperfusion device, which comprises a construction method of an endotoxemia rabbit model and comprises the following steps: injecting a bacterial liquid containing bacteria into a rabbit once to generate endotoxin in the rabbit body, the type of the bacteria is escherichia coli, the injection dosage of the bacterial liquid is 0.1-2mL, the OD600 value of the bacterial liquid is 1.3-1.7, and the endotoxin is generated in the rabbit body. And injecting the bacterial liquid for at least 3h to obtain the endotoxemia rabbit model. The endotoxemia rabbit model is used as an animal model for evaluating the endotoxin adsorption performance of the hemoperfusion device, the influence of factors of an animal body on the endotoxin concentration can be eliminated, and the endotoxin adsorption performance of the hemoperfusion device can be accurately and objectively evaluated.

The invention discloses a method for regulating and controlling synthesis of ectoine in escherichia coli, and relates to the technical field of biological medicines. According to the method for regulating and controlling the synthesis of the ectoine in the escherichia coli, disclosed by the invention, a gene segment of a tisB toxic protein is used for constructing a tisB toxic protein expression vector pET28a (+)-p2-22-tisB, and the tisB toxic protein expression vector is transferred into an escherichia coli engineering bacterium for synthesizing the ectoine, so that the escherichia coli engineering bacterium E.coli Ect pET28a (+)-p2-22-tisB for spontaneously inhibiting the synthesis of the ectoine is obtained, and meanwhile, the normal synthesis of the ectoine at an early stage can be ensured. The nucleotide sequence of the gene segment of the tisB toxic protein is as shown in SEQ ID NO. 1. In the first three rounds of fermentation, the yield of ectoine is close to that of the control engineering bacteria; after the seventh round, the yield of ectoine is sharply reduced to 2.575 g / L, and during the twentieth round of fermentation, the yield of ectoine is zero.

The invention provides a preparation method and application of tannic acid and panax notoginseng total saponins composite drug-loaded multifunctional hydrogel, and relates to the technical field of biomedical materials.Chitosan, one of the components of the hydrogel, is subjected to carboxymethylation modification to form carboxymethyl chitosan, the carboxymethyl chitosan and aldehyde-modified xanthan gum are subjected to a Schiff base reaction, and the hydrogel is prepared into the multifunctional drug-loaded tannic acid and panax notoginseng total saponins composite drug-loaded multifunctional hydrogel. Meanwhile, tannic acid and panax notoginseng saponins are loaded, and the composite hydrogel is obtained. The hydrogel loaded with the tannic acid and the panax notoginseng saponins, provided by the invention, carries the tannic acid and the panax notoginseng saponins as active substances, can keep the activity of the medicine for a long time, and has good injectability, self-healing property and wound exudate absorption property, the tannic acid can inhibit inflammatory response and reduce the generation and release of inflammatory factors, and the hydrogel loaded with the tannic acid and the panax notoginseng saponins can be used for treating wound exudate. The tannic acid has a wide antibacterial property, such as IL-1beta, IL-6, TNF-alpha and the like, and can inhibit the growth and reproduction of various bacteria, including common pathogenic bacteria such as staphylococcus aureus, escherichia coli and the like.

The invention belongs to the technical field of genetic engineering, and discloses a plasmid-free genetically engineered bacterium for efficiently synthesizing gamma-aminobutyric acid from beginning by taking a cheap carbon source as a substrate, a method and application of the genetically engineered bacterium. The genetically engineered bacterium is obtained by overexpressing a T7RNA polymerase gene on the basis of a wild type E.coli MG1655; the gene gabT and the gene puuE are deleted; performing overexpression on the genes of gadC, gadbm, gdh, gltA, pyc and ppc; and the expression of sucA and argA genes in a GABA channel produced by escherichia coli is dynamically regulated and controlled by using a growth coupled promoter. The genetic manipulation of the engineering bacterium is carried out on a genome, plasmid residues, antibiotics and inducers are not used, the production performance is stable, and the fermentation process is simple. The engineering bacteria are used for fermenting for 38 hours under a staged pH value control process, the yield of gamma-aminobutyric acid can reach 35.4 g / L, and the engineering bacteria have a relatively good industrial application value.