125 results about "Bacillus coli" patented technology

The invention relates to a development method of an insect culture medium, which comprises the following steps: S1, constructing a double-promoter tandem vector by taking pFastBac plasmid as a skeleton; s2, establishing a baculovirus expression system; S21, transforming the double-promoter tandem vector into DH10Bac escherichia coli, so as to obtain recombinant Bacmid; s22, transfecting an Sf9 cell by using the recombinant Bacmid, so as to obtain a P0-generation baculovirus; s23, transfecting an Sf9 cell by using the P0-generation baculovirus to obtain a P1-generation baculovirus; s3, screening insect culture media: S31, providing culture media to be detected, and respectively inoculating Sf9 cells into the culture media to be detected; s32, respectively inoculating the P0-generation baculovirus or the P1-generation baculovirus into each to-be-detected culture medium for culturing; and S33, after culture is finished, detecting virus antibodies in the culture media to be detected, and screening the culture media. A comprehensive and quantitative evaluation system is established for development of the insect culture medium.

The invention belongs to the technical field of genetic engineering, and discloses a bacillus thuringiensis-sourced brown planthopper-resistant insecticidal protein and a coding gene and application thereof, the bacillus thuringiensis-sourced brown planthopper-resistant insecticidal protein is an insecticidal protein orf1715, the amino acid sequence is shown as SEQ ID NO: 1, and the nucleotide coding sequence of the gene is shown as SEQ ID NO: 2. The gene is well expressed in an escherichia coli system in a soluble form, and the purified protein has a remarkable specific insecticidal effect on rice pest brown planthopper, so that the gene can be applied to special prevention and control of brown planthopper, and a candidate gene resource is provided for cultivation of a new transgenic insect-resistant rice variety.

The invention belongs to the technical field of building materials, and particularly relates to a preparation method of alkali-treated polypropylene fiber and recycled aggregate loaded bacillus coriolis synergistic microbial concrete. According to the method, a polypropylene fiber reinforced concrete matrix is subjected to alkali treatment, calcium carbonate is generated by combining the mineralization effect of recycled aggregate loaded microorganisms, and efficient crack repair and mechanical property improvement are achieved. The method specifically comprises the steps of microbiological treatment and loading, fiber surface modification and optimization, self-healing concrete preparation and the like. The recycled aggregate is used for fixing microorganisms and providing a mineralization environment, the interface bonding capacity is enhanced through alkali treatment fibers, and the calcium carbonate deposition efficiency is remarkably improved. The prepared self-healing concrete has excellent mechanical strength and compactness, and the repairing performance is also obviously improved. The method is simple in process and controllable in cost, the utilization of the recycled aggregate conforms to the concept of green building materials, and the method can be widely applied to preparation of microbial concrete and has remarkable environmental protection value and application prospects.

The invention provides a biodegradable food preservative film as well as a preparation method and application thereof. The preservative film is a chitosan and polyvinyl alcohol composite film loaded with cinnamon oil microcapsules. The preparation method mainly comprises microcapsule preparation and film preparation. Wherein the microcapsule preparation comprises the following steps: dissolving beta-cyclodextrin, adding cassia oil, and stirring the mixture to form a microcapsule emulsion. And storing the emulsion in a refrigerator overnight. And on the second day, filtering the solution to collect a precipitate, washing and drying to obtain the microcapsule. The film preparation comprises the step of mixing a polyvinyl alcohol solution, a chitosan solution and glycerol according to a fixed proportion. Then, adding cassia oil microcapsules, and uniformly stirring to obtain a film-forming solution; and pouring the film forming liquid into a mold flat plate to prepare a film, thereby obtaining the antibacterial composite film. The tear strength of the prepared film is 21.18 N / mm < 2 > to 43.21 N / mm < 2 >, the elongation at break is 82.60% to 147.56%, and the antioxidant activity is 27.47% to 36.87%; the preservative has an obvious inhibiting effect on staphylococcus aureus and escherichia coli, and can effectively prolong the shelf life of fresh-cut fruits.

The invention belongs to the field of biotechnology and environmental governance, and particularly relates to a manganese peroxidase mutant based on high-throughput screening modification and application of the manganese peroxidase mutant to straw degradation. Aiming at the problems of low natural secretion amount, insufficient specific activity, complex preparation process and the like of the existing manganese peroxidase, the method comprises the following steps: firstly, constructing engineering bacteria based on an escherichia coli exocrine system, constructing a mutant library through error-prone PCR in combination with a directed evolution technology, and performing high-throughput screening by utilizing an ABTS colorimetric method; the recombinant manganese peroxidase mutant with high catalytic activity is obtained, and the enzyme activity is improved by 1.29 times compared with that of a wild type. Furthermore, recombinant engineering bacteria are constructed on the basis of a bacillus subtilis exocrine system, and efficient secretion of the mutant enzyme is achieved. The mutant enzyme preparation is used for wheat straw degradation, and the lignin degradation rate reaches 41.37% (improved by 30.09% compared with that of a wild type). The method is simple and convenient in process, low in cost and remarkable in effect, and has a wide industrial application prospect.

The present invention relates to the technical field of silk modification, and in particular, designs a novel antibacterial silk and a preparation method. A preparation method of a novel antibacterial silk comprises the following steps: S11: soaking the silk in a finishing solution A for 5 to 50 minutes, and performing a first antibacterial finishing; S12: alcoholizing the silk after the first antibacterial finishing in 10 to 20°C ethanol for 20 seconds to obtain alcoholized silk; S13: directly soaking the alcoholized silk in step S12 in a finishing solution B for 0.5 to 5 hours at a soaking temperature of 10 to 20°C, and performing a second antibacterial finishing; S14: drying the silk after the second antibacterial finishing to obtain antibacterial silk. The preparation method of the present invention is simple, the process conditions are mild, the prepared silk has a good antibacterial effect, and is widely used in clothing, home textiles, medical and other fields. The prepared antibacterial silk has excellent antibacterial performance, and the antibacterial rates of Staphylococcus aureus and Escherichia coli are both greater than 92% after washing 50 times.

The invention belongs to the technical field of biology, and particularly relates to recombinant escherichia coli for producing curcumin glucoside and application of the recombinant escherichia coli. According to the invention, escherichia coli BL21 (DE3) is taken as a host cell, and a double mutant of a polyphenol TDP-rhamnosyltransferase ppuG gene derived from bacillus subtilis 168, a glucose-6-phosphate mutase Pgm gene derived from escherichia coli MG1655 and a UDP-glucose pyrophosphorylase GalU gene are transferred into the escherichia coli host cell, so that the recombinant escherichia coli is obtained. The double mutants of the polyphenol TDP-rhamnosyltransferase ppuG gene comprise two mutation sites, namely, G51A and Q345R. The invention further discloses a preparation method of the polyphenol TDP-rhamnosyltransferase ppuG gene. The recombinant escherichia coli constructed by the invention can efficiently produce curcumin diglucoside, and the yield can reach 7.10 g / L, so that not only are the water solubility and bioavailability of curcumin improved, but also powerful support can be provided for industrial production of curcumin glucoside.

The invention discloses a purification method for removing endotoxin in prokaryotic expression recombinant protein, which belongs to the technical field of bioengineering, and comprises the following steps: adding 0.1% Triton X-114 in an ultrasonication stage, carrying out ice-bath ultrasonication, after the recombinant protein is combined with a Ni-NTA affinity column, washing with 50 column volumes of a combination buffer solution containing 0.1% Triton X-114, and carrying out elution by using an elution buffer solution containing 0.1% Triton X-114 in the presence of an elution buffer solution containing 0.1% Triton X-114 in the presence of an elution buffer solution containing 0.1% Triton X-114 in the presence of an elution buffer solution containing 0.1% Triton X-114; and washing with a 4-DEG C binding buffer solution with 20 column volumes, and subsequently eluting the target protein with imidazole with different gradients. Then, regulating the pH value of the purified recombinant protein solution to 2-4 or more than 10 through 100mM hydrochloric acid or sodium hydroxide, dissociating and decomposing endotoxin, carrying out oscillation treatment at room temperature for 2-4 hours, then removing the endotoxin in the recombinant protein through ultrafiltration, retaining an endotube protein solution, and detecting the content of protein and the endotoxin in the recombinant protein; the method is easy and convenient to operate and low in cost, the endotoxin content in the recombinant protein prepared through prokaryotic expression can be reduced by 400 times on the premise that immune recognition of the recombinant protein and serum is not affected, and the phenomenon that strong cross reaction occurs between immune serum and escherichia coli due to high endotoxin residues in the recombinant protein is reduced.

The present invention discloses a method and application for efficiently producing cytidylic acid, and belongs to the field of biotechnology. The present invention integrates the pyrimidine operon gene cluster pyr_Bs of Bacillus subtilis at the gene locus pta, reconstructs the UMP synthesis pathway in Escherichia coli, improves the metabolic flux of the 5'-cytidylic acid synthesis pathway, and realizes efficient production of 5'-cytidylic acid (5'-CMP). The yield of 60h fermentation in a 60L fermenter reaches 49g / L.

The invention belongs to the technical field of gene engineering, and in particular relates to a D-psicose-3-epimerase mutant subjected to Spytag / SpyCatcher cyclization modification and an application of the D-psicose-3-epimerase mutant. The preparation method comprises the following steps: carrying out multi-site simultaneous mutation on 109th aspartic acid and 160th serine of wild type D-psicose-3-epimerase to obtain a mutation intermediate, respectively connecting a Spytag tag and a SpyCatcher tag to the N end and the C end of the mutation intermediate, and carrying out cyclization modification, so as to obtain the wild type D-psicose-3-epimerase, wherein the Spytag tag and the SpyCatcher tag are respectively connected to the N end and the C end of the mutation intermediate; when fructose is used as a raw material to produce D-psicose and host bacteria are escherichia coli, the reaction of catalyzing 600 g / L fructose to produce D-psicose is performed for 4 h, and the conversion rate can reach 35.7%; when the host bacteria are bacillus subtilis, the reaction for catalyzing 500 g / L fructose to produce D-psicose is performed for 4 h, and the conversion rate reaches 36.5%; compared with a wild type D-psicose-3-epimerase strain of bacillus subtilis, the conversion rate of the strain is improved by 13.5%.

The application discloses a method for improving the fermentation efficiency of soy sauce pool type fermentation, which is characterized by the following steps: using the self-source microorganism in the fermentation tank to carry out fermentation outside the fermentation tank, combining with the fermentation liquid of Lactobacillus reuteri for synergistic fermentation, and then returning the fermentation liquid to the fermentation tank for pouring and utilization, so as to realize the promotion of the self-source microorganism in the fermentation tank to the soy sauce fermentation. The self-source microorganism is fermented and cultured by reducing the salinity outside the fermentation tank and adding a proper amount of starch raw material, and the fermentation liquid with high activity of protease can be prepared in a short time, which is returned to the fermentation tank for pouring and utilization, so as to improve the degree and efficiency of protein hydrolysis in the fermentation tank. The Lactobacillus reuteri uses the fermentation liquid of the soy sauce mash in the fermentation tank as the basic nutrient source and ferments together with a proper amount of white granulated sugar to produce the fermentation liquid with the function of inhibiting Escherichia coli, so as to resist the Escherichia coli pollution in the fermentation process of the self-source microorganism outside the fermentation tank, guarantee the safety of the returned pouring fermentation liquid, and further improve the production efficiency of the soy sauce pool type fermentation technology.

Cyclic dinucleotides, which are a type of signaling substance for cancer treatment, are secondary messengers of intracellular events initiated by GPCR activation and act as a stimulator of interferon genes (STING), and thus can have a significant effect on tumor suppression. Meanwhile, when cancer occurs in a subject, angiogenesis and cell growth proceed at a very high rate in the body, and thus an oxygen-deficient environment is created due to incomplete angiogenesis in cancer tissues, which may be very suitable for the proliferation of anaerobic bacteria such as Salmonella sp. strains or E. coli. Therefore, the present invention relates to a DNA construct into which is introduced a gene for an enzyme that synthesizes a signaling substance for cancer treatment, e.g., a cyclic dinucleotide, or to a strain transformed with a vector comprising the DNA construct. The DNA construct or the strain transformed with a vector comprising the DNA construct, according to the present invention, targets cancer in a subject and then secretes C-di-AMP or C-di-GMP synthase in the surrounding environment of the cancer, and thus can very effectively prevent or treat cancer and, at the same time, can diagnose cancer in real time.

The invention provides a beta-glucosidase mutant from Paenibacillus phyllosphaerae, and a method for efficiently preparing rare ginsenoside F2 by using an enzyme method and a whole-cell method, and particularly provides a beta-glucosidase mutant from Paenibacillus phyllosphaerae and a method for efficiently preparing rare ginsenoside F2 by using a beta-glucosidase mutant from Paenibacillus phyllosphaerae. The method comprises the following steps: engineering-modifying beta-glucosidase by utilizing computer-aided design, constructing a mutant library, carrying out primary screening and secondary screening to obtain two high-activity mutants Q7D and G189A, constructing a combined mutant Q7D / G189A, transforming the combined mutant Q7D / G189A into genetically engineered bacterium escherichia coli for expression, and producing F2 by utilizing a whole-cell method. Finally, the highest yield of 18.01 g / L is achieved after the reaction is carried out for 10 h in a 5 L fermentation tank and is 6.82 times that of a shake flask, and the purity of F2 reaches up to 82.20% after the reaction is carried out for 24 h finally. The invention not only provides an efficient solution for large-scale production of rare saponin F2, but also provides a transferable framework for designing and engineering diversified glycoside hydrolase in customized biological catalysis.

The invention discloses the application and method of Leuconostoc mesenteroides in the preparation of fermented food or beverage, and relates to the field of microbial fermentation technology. Leuconostoc mesenteroides I1 / 53 produces antibacterial components such as hydrophilic esters, thioaminophenol C, cerulenin and faecalis in fermented sugarcane juice beverage, which can effectively inhibit foodborne pathogens, including Staphylococcus aureus, Escherichia coli, Salmonella, Listeria monocytogenes, Staphylococcus lentus, Bacillus subtilis, Bacillus cereus and Micrococcus luteus; at the same time, it can also enhance the flavor characteristics of sugarcane juice beverage.

The invention discloses a Rogowski eutrophy alkali-producing engineering strain for producing p-coumaric acid as well as a construction method and application of the Rogowski eutrophy alkali-producing engineering strain. The preparation method comprises the following steps: by taking a chemoautotrophic microorganism Ropriavidus alcaligenes H16 as an original strain, firstly, by knocking out a synthetic route of a strain poly-3-hydroxybutyrate (PHB), introducing a tyrosine ammonia lyase gene from Rhodotorula glutinis to construct a basic engineering strain capable of producing p-coumaric acid, and then, carrying out fermentation on the basic engineering strain to obtain the p-coumaric acid. Then, endogenous 3-deoxy-7-phosphoheptanone acid synthase gene aroG1 and chorismate synthase gene aroC are overexpressed, and the total copy is increased, so that the p-coumaric acid synthetic pathway flux of the engineering strain is enhanced; and introducing NAD (P) transhydrogenase gene pntAB from Escherichia coli to improve the supply of cofactors, so as to finally obtain the eutrophy alcaligenes Rosei engineering strain capable of synthesizing p-coumaric acid by using CO2.

The present invention relates to a composition that is used to primarily disrupt and remove biofilm from surfaces. This is achieved using a composition comprising a bacteriophage capable of lysing bacteria selected from one or more of Pseudomonas aeruginosa, Acinetobacter baumanii, Staphylococcus aureus, and E.coli; and a Bacillus bacterial spore in the presence of a specific surfactant of the poloxamer type.

The invention belongs to the field of microbial technology, and specifically relates to a strain of acid fish lactobacillus PKC6 and an application thereof. The acid fish lactobacillus PKC6 is deposited in the General Microbiological Center of the China Microbiological Culture Collection Administration Committee, and the deposit number is CGMCC NO. 27201. The new strain of acid fish lactobacillus PKC6 screened by the invention is resistant to gentamicin, polymyxin B, vancomycin, kanamycin and norfloxacin, sensitive to ampicillin, penicillin, cephalexin and doxycycline, and has a good inhibitory effect on Escherichia coli and Staphylococcus aureus; the strain screened by the invention, after being compounded with a composite enzyme and co-fermented with palm meal, can greatly increase the content of nutrients in the fermentation product, and has a more obvious promoting effect on the intestinal development of raised animals, thereby achieving the purpose of improving the palatability of feed and promoting intestinal development.

The invention belongs to the technical field of membrane separation, and particularly relates to a quercetin-doped reverse osmosis composite membrane, a preparation method thereof and a water purification method. The quercetin-doped reverse osmosis composite membrane comprises a polysulfone microfiltration base membrane and a quercetin-doped polyamide selection layer, the quercetin-doped polyamide selection layer is attached to the surface of at least one side of the polysulfone microfiltration base membrane; the quercetin-doped polyamide selection layer comprises quercetin and a polyamide skeleton, and the quercetin and the polyamide skeleton are connected through an ester bond and / or a hydrogen bond. The quercetin-doped reverse osmosis composite membrane at least meets one of the following conditions: the surface roughness is 121 nm to 199 nm; the water contact angle is 50-60 degrees; under the conditions of 20 bar and 25 DEG C + / -1 DEG C, the retention rate on a 2000 mg.L <-1 > NaCl solution is greater than or equal to 95%; the Zeta potential is-30mV to-60mV when the pH value is equal to 7; the sustained release rate of quercetin is 0.1 [mu] g.cm <-2 >. D <-1 >-10 [mu] g.cm <-2 >. D <-1 >; the killing rate of escherichia coli is greater than or equal to 90%; and the killing rate of staphylococcus aureus is greater than or equal to 90%.

The present invention relates to a recombinant bacterium producing Arctic-derived β-glucosidase and its application, belonging to the field of biotechnology. The target gene of the recombinant bacterium is β-glucosidase derived from Arctic bacteria Arc12, the nucleotide sequence of which is shown in SEQ ID No: 1, and the nucleotide sequence of the β-glucosidase with signal peptide is shown in SEQ ID No: 2, the signal peptide is Bacillus subtilis signal peptide CitH, and the expression vector is Escherichia coli-Bacillus shuttle plasmid pMA5, which contains constitutive promoter P HpaII The expression strain is Bacillus subtilis WB600. The present invention provides a method for secretory expression of the enzyme under specific promoter, signal peptide, and strain conditions. This method is simple to operate and can be achieved without the need for special inducers. Secretory expression of the enzyme eliminates the need for cell disruption in downstream processing, reducing production costs and possessing promising application prospects.

The invention relates to a method for extracting roselle anthocyanin through enzymolysis-ultrasonic assistance, a product and application of the product. The method comprises the following steps: degreasing roselle powder, and performing enzymolysis for 24 hours by using cellulase and pectinase (20U / g respectively) under the conditions that the pH is 5.0 and the temperature is 40 DEG C; an acetone-hydrochloric acid mixed solution (the volume fraction of hydrochloric acid is 36%) with the liquid-material ratio being 10: 1 serves as an extracting agent, and ultrasonic extraction is conducted for 34 minutes at the temperature of 58 DEG C and the power of 160 W; and finally, centrifuging, extracting with ethyl acetate, and purifying to obtain an anthocyanin product. According to the method, the extraction rate reaches 3.087 mg / g, the main component of the product is cyanidin-3-glucoside, the antioxidant and antibacterial activity is remarkable, the scavenging rates of DPPH, ABTS and hydroxyl radicals are 86.26%, 81.34% and 93.75% respectively under the concentration of 3.0 mg / mL, and the scavenging rates are superior to those of vitamin C with the same concentration; under the concentration of 11mg / mL, the compound has an obvious inhibition effect on escherichia coli and staphylococcus aureus. The process is efficient and mild, the product activity is excellent, and the method is suitable for development and application of natural antioxidants and antibacterial agents.

The application discloses a colloidal gold test strip for distinguishing between wild toxin infection and vaccine immunization of porcine pleuropneumonia actinobacillus and application. The test strip of the application takes ApxIVA truncated protein with an amino acid sequence shown as SEQ ID NO. 3 as an antigen, the truncated protein can be soluble expressed in E. coli, and the structure and function of the truncated protein are close to those of natural apxIVA. The test strip of the application comprises a sample pad, a colloidal gold pad, an NC membrane, a water absorption filter paper and a bottom plate, the colloidal gold pad is coated with gold-labeled apxIVA truncated protein and gold-labeled chicken IgY antibody, and the C line and the T line of the NC membrane are fixed with goat anti-chicken IgY antibody and apxIVA truncated protein. The test strip only needs 25 muL of pig serum to make detection within 5-10 min, and can distinguish between APP wild strain infection and gene deletion vaccine APP-HB-04M immunized serum samples.

The present invention discloses a bifunctional thienyl COF composite fiber having both photocatalytic antibacterial and degradation of mustard gas simulants and a preparation method thereof. The present invention uses benzo[1,2-B:3,4-B':5,6-B']terthiophene-2,5,8-trialdehyde and an amino compound to synthesize a stable two-dimensional COF by a solvothermal method, and the COF is loaded on an acrylic acid-modified non-woven fabric to prepare a COF composite fiber. The COF composite fiber has an antibacterial rate of more than 99% against Gram-positive Bacillus subtilis and Gram-negative Escherichia coli under simulated sunlight, has good photocatalytic activity for the degradation of 2-CEES, and has a degradation rate of 2-CEES greater than 99% after at least 5 cycles of photocatalytic decontamination cycles. The COF composite fiber of the present invention is a potentially efficient composite material for decontaminating pathogens and chemical agents, and has great application potential in biochemical protective equipment for preventing public safety.

The application discloses an L-aspartate alpha-decarboxylase with improved substrate tolerance, and the L-aspartate alpha-decarboxylase is derived from Bacillus subtilis and is subjected to site-directed mutation, i.e., phenylalanine at the 4th site is changed into tryptophan, isoleucine at the 33rd site is changed into alanine, and isoleucine at the 88th site is changed into tryptophan, so as to obtain an enzyme mutant; the mutant is recombined into E. coli, and after expression is induced, the mutant catalyzes the substrate L-aspartate to generate beta-alanine. When the substrate addition concentration of the whole cell catalytic system is 60 g / L, the conversion rates of the three enzyme mutants T4W, I33A and I88M can reach about 90%, and the yields are 1.2, 1.3 and 1.2 times of that of the unmutated strain respectively, and the substrate tolerance is obviously improved; the combined mutation also has a certain improvement on the substrate tolerance, and the finding has important research value for industrial preparation of beta-alanine.

The present invention provides a modified akebia pectin, a preparation method and an application thereof, and belongs to the technical field of biomacromolecule processing. The present invention degrades and modifies akebia pectin through specific enzymolysis and dielectric barrier discharge plasma treatment steps, thereby overcoming the problem that the degradation and modification method of akebia pectin in the prior art has poor effect. The modified akebia pectin obtained by the degradation and modification method of akebia pectin provided by the present invention can achieve good antibacterial effects on Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, successfully achieving a significant change in the biological activity of akebia pectin polysaccharides, and has important practical significance for developing akebia pectin resources and enhancing its utilization value.

The invention belongs to the technical field of food-borne pathogenic microorganism detection, and particularly relates to an ortho-position nucleic acid probe for detecting norovirus and application of the ortho-position nucleic acid probe. The invention provides an ortho-position nucleic acid probe for identifying norovirus, the ortho-position nucleic acid probe specifically comprises a polystyrene nanoprobe and a single-chain binding protein coupling probe, and the polystyrene nanoprobe is formed by covalent binding of polystyrene microspheres, lectin and hairpin DNA. The single-chain binding protein coupling probe is formed by combining a norovirus antibody and a nucleic acid molecule through a connecting molecule. The probe is simple in synthesis condition and does not need complex purification steps. According to the present invention, a combined reaction with an activation chain, a hybridization chain reaction reagent and a catalytic self-assembly reagent is performed, and the detection sensitivity is improved through a signal cascade amplification reaction, and can achieve the minimum of 0.15 pg mL <-1 >; and moreover, the gene has excellent specificity, and the delta F'difference between the gene and pathogens of staphylococcus aureus, escherichia coli, rotavirus and astrovirus is extremely remarkable.

The present application belongs to the technical field of biological agents, and discloses a compound preparation containing bacillus velezensis and piper betel for preventing and treating avian colibacillosis and application. The mass ratio of the bacillus velezensis complex bacteria and the piper betel extract is 2-4:0.02-0.03; the bacillus velezensis is named as BV-838 and BV-839. It is proved by tests that the bacillus velezensis and the piper betel compound preparation have potential interaction, can cooperate with each other, play synergistic effect, can effectively prevent and treat avian colibacillosis, have the effect of enhancing immunity and promoting growth, are novel, efficient, green and environmentally friendly, and have important significance for the development of non-antibiotic breeding industrialization.

The present invention provides a broad-spectrum antimicrobial peptide AG3 and a preparation method and application thereof, belonging to the field of biotechnology, and the amino acid sequence thereof is shown in SEQ ID No. 1. The antimicrobial peptide AG3 of the present invention has a significant inhibitory effect on 11 Gram-negative and Gram-positive bacteria and fungal species such as Escherichia coli, Pseudomonas aeruginosa, Salmonella pullorum, Staphylococcus aureus, and Candida albicans, and the average antibacterial activity reaches 2 μM; the bactericidal power also shows that it has a high bactericidal ability against bacteria; at the same time, its hemolytic activity is low, and the therapeutic index is as high as 32; in addition, it still has good antibacterial activity in physiological concentration salt ions, indicating that it has a high salt ion tolerance, and related mechanism experiments prove that it realizes antibacterial function through a physical membrane rupture mechanism.

The present invention discloses a strain of Bacillus Velez CB6 and the antimicrobial protein produced and its application, belonging to the field of microbial application technology. The deposit number of the Bacillus Velez CB6 is CGMCC NO.30515. The strain has a good antagonistic effect on Gram-negative bacteria such as multidrug-resistant Escherichia coli. The antimicrobial protein CB6-E prepared by fermentation of the strain shows good antimicrobial activity against a variety of Gram-negative bacteria, and has good safety for a variety of animals. CB6-E has a good therapeutic effect on mice and wax moths infected with polymyxin-resistant and carbapenem-resistant Escherichia coli. The antimicrobial protein CB6-E prepared by fermentation of Bacillus Velez CB6 of the present invention is expected to enrich the current existing antimicrobial drug library and provide new hope for the treatment of multidrug-resistant Gram-negative bacterial infections.

The invention discloses a method for extracting polygonatum sibiricum seed volatile oil by assisting steam distillation and application. The method comprises the following steps: removing petioles of fresh polygonatum sibiricum fruits, discarding bad fruits, crushing and removing peels; washing and pre-drying the polygonatum sibiricum seeds; the separated polygonatum sibiricum seeds are crushed, and hard seeds are crushed; collecting and storing all seed powder; extracting volatile oil by adopting a volatile oil extractor, determining an optimal extraction process of the polygonatum sibiricum seed volatile oil, and collecting the volatile oil. According to the invention, the components of the polygonatum sibiricum seed volatile oil are analyzed to determine that the extraction process greatly improves the extraction rate of the polygonatum sibiricum volatile oil and promotes the utilization rate of polygonatum sibiricum; the extraction method is green and efficient, does not use an organic solvent, is simple to operate, has low requirements on equipment and is beneficial to subsequent industrial production; the method can be applied to extraction of rhizoma polygonati volatile oil in other parts such as rhizoma polygonati rhizomes and leaves. And the extracted volatile oil has an inhibition effect on escherichia coli, staphylococcus aureus, bacillus subtilis, candida albicans and the like, and can be used as a bacteriostatic agent.