411 results about "Point mutation" patented technology

The invention discloses a glycosyl transferase mutant and an application of the glycosyl transferase mutant in synthesis of rebaudioside. According to the invention, single-point mutation and multi-point mutation are carried out on the basis of a glycosyl transferase amino acid sequence as shown in SEQ ID NO: 1, and a mutant with improved catalytic activity is obtained. The catalytic activity, the substrate specificity and / or the substrate specificity of the glycosyl transferase mutant are / is changed, and the catalytic activity of enzyme to a specific substrate can be remarkably improved by mutation at a specific site. And carrying out induced expression and protein purification on the obtained mutation sequence to obtain the mutant enzyme. The mutant enzyme is used as a catalyst, and UDPG is used as a glycosyl donor, so that the catalytic reaction efficiency of substrates such as stevioside ST, rebaudioside A (RebA) and rebaudioside D (RebD) can be obviously improved. According to the glycosyl transferase UGT76G1 mutant constructed by the research, the catalytic activity of the glycosyl transferase UGT76G1 mutant is improved, and efficient production of rebaudioside M is realized by optimizing a reaction system.

The invention discloses a high-efficiency lysine decarboxylase mutant and an application of the high-efficiency lysine decarboxylase mutant in synthesis of pentamethylene diamine. A series of mutants including a single mutant (such as N218G, T222V, C244P and the like), a double mutant and a three mutant are obtained by carrying out multi-site mutation on wild type lysine decarboxylase (SEQ ID NO.2) from Klebsiella grimontii. The catalytic efficiency of the mutant is remarkably improved, and the activity of the mutant is improved by 5.0-10.2 times compared with that of a wild type enzyme. According to the method disclosed by the invention, the substrate conversion rate of 99% or above can be realized within 2 hours through an optimized process of constructing an expression vector and a genetically engineered bacterium, inducing expression of lysine decarboxylase and synthesizing 1, 5-pentanediamine by utilizing a whole-cell catalysis technology. Compared with a traditional chemical method and a natural enzyme method, the method disclosed by the invention has the advantages of simplified process, high catalytic efficiency, low production cost and the like, and is suitable for producing bio-based 1, 5-pentamethylene diamine and nylon 56 salt.

The invention belongs to the technical field of microbial genetic engineering, and particularly relates to an alpha-2, 3-sialyltransferase mutant and application thereof. The a-2, 3-sialyltransferase mutants V175N, P198A, G173D, D174Q, F196K and A315H are obtained by performing site-specific mutagenesis on six amino acids in an a-2, 3-sialyltransferase amino acid sequence coded by a gene derived from Campylobacter jejuni (OH4384), the yield of 3 '-sialyllactose is remarkably increased by single-point mutagenesis of the V175N, the yield of 3'-sialyllactose is remarkably increased by single-point mutagenesis of the V175N, the yield of 3 '-sialyllactose is remarkably increased by single-point mutagenesis of the P198A, the G173D, the D174Q, the F196K and the A315H, the optimal recombinant microbial strain 3 '-SL-09 (V175N / P198A / D174Q) is obtained through combination of multiple mutation sites, the yield can reach 5.91 g / L, the bottleneck problem of low catalytic efficiency of sialyltransferase is effectively solved, and an enzyme element with excellent performance is provided for high-efficiency and low-cost biological manufacturing of 3'-SL.

The invention provides a nucleotide mutation site prediction model construction and disease-related point mutation identification method. Specifically, the invention provides a deep learning model-fused nucleotide mutation site prediction model construction method and a disease-related point mutation identification method. According to the method, DNA point mutation and RNA point mutation can be recognized from transcriptome sequencing data in a high-sensitivity and high-specificity mode, and basic data is provided for explaining mutation generation mechanisms and functions on the whole transcriptome and genome level.

The invention belongs to the technical field of biosynthesis, and particularly relates to an engineering bacterium for preparing stevioside through de novo fermentation as well as a preparation method and application of the engineering bacterium. According to the invention, mevalonate kinase in the MVA pathway is mutated and optimized. The method comprises the following steps: carrying out point mutation on mevalonate kinase MvK of a wild type source, constructing a stevioside synthesis route in an escherichia coli host, and comparing the influence of MvK mutation on the yield of stevioside, so as to determine a Q160L mutant, and applying the Q160L mutant to the stevioside production route to realize efficient production of stevioside.

To improve allele discrimination, the inventors adapted the system combining Cas13a detection sensitivity with allele-specific PCR amplification to propose CASPER (Cas13a Allele-Specific PCR Enzyme Recognition) as a new versatile, easy-to-implement, and highly sensitive method to detect low-frequency of sequence variant. CASPER enabled specific and sensitive detection of KRASG12D with low DNA input such as DNA extracted from patient's pancreatic ultrasound-guided fine-needle aspiration fluids. CASPER is easy to implement and a versatile reliable method virtually adaptable to any point mutation.

The invention provides a primer probe set for digital PCR detection of non-small cell lung cancer EGFR mutation and application thereof, and relates to the technical field of digital PCR detection, the primer probe set comprises a primer pair and a probe for specific detection of EGFR gene exon 19 deletion mutation (19del) and exon 21 L858R point mutation, and the 19del mutation probe comprises a plurality of sequences to cover common subtypes. The primer probe group can be combined with a microfluidic digital PCR platform for use, a sample is divided into tens of thousands of microdroplets for amplification, and FAM, HEX, ROX and CY5 fluorescence channel signals are detected to realize absolute quantification. The system provided by the invention has high sensitivity and excellent linearity and precision, is particularly suitable for detecting extremely-low-frequency EGFR mutation in body fluid such as plasma, and has important application value in individualized diagnosis and treatment, curative effect monitoring and drug resistance evaluation of non-small cell lung cancer.

The invention relates to an islet repair ICK mode oral polypeptide optimization system taking VDAC1 as a target based on ESM2 and a genetic algorithm, and the system comprises a mutation module which is used for carrying out mutation and recombination by adopting the genetic algorithm according to original protein sequence data to generate an initial population; the prediction module is used for respectively inputting the protein sequence data of the initial population into a protein dimer dissociation energy prediction model, a protein toxicity prediction model and a protein cell penetrability prediction model to obtain a dissociation energy prediction value delta G, a toxicity probability value T and a cell membrane passing transmission probability Ed; and the optimization module is used for acquiring the optimal individual performance of the highest fitness score to output the Pareto optimal sequence index, and recording the hotspot residue distribution and the site mutation frequency at the same time. On the basis of keeping the biological activity of the original sequence, the key drug properties are improved in a breakthrough manner.

The invention discloses a cellobiose 2-epimerase mutant as well as a gene, an expression vector, recombinant bacteria, a preparation method and application thereof. The mutant is obtained by performing the following point mutation on an amino acid sequence as shown in SEQ ID No.1: S12A, S24A, G131A, G176A, G224A, K46R, K69R, K72R, K91R, K103R, K201R, K219R, K223R, K241R, K263R, K266R, K273R, K284R, K325R, K335R, K349R and K387R. The invention further discloses a preparation method of the mutant. The invention further discloses a gene segment, a plasmid and a recombinant bacterium for recombinant expression of the mutant, and the gene segment, the plasmid and the recombinant bacterium are used for recombinant expression preparation of the mutant. The mutant can be used for continuously and stably catalyzing and preparing lactulose at high temperature, is relatively good in thermal stability and has a relatively good industrial application prospect.

The invention discloses application of novel reverse transcriptase and related fusion protein of the novel reverse transcriptase in plant-guided editing. Candidate RT protein is obtained through systematic mining from a public database, novel reverse transcriptase cl1 with activity is screened out in combination with a fluorescence report system, and a guided editing system suitable for plants is constructed. The system tests in wheat protoplast, and verifies the editing activity of cl1 to a plurality of endogenous targets. Further combining with protein structure prediction and rational design point mutation optimization, the cl1 mutant with higher editing efficiency is obtained, and the method can be applied to accurate and effective editing of plant genomes and plant breeding and improvement.

The invention discloses a reverse transcriptase, wherein a coding sequence of the reverse transcriptase is derived from a Rattus norvegicus genome. The protein sequence of the protein comprises a protein sequence of a wild type Rattus norveicus, or a protein sequence which is subjected to engineering modification on the basis of the wild type Rattus norveicus, or a protein sequence which is subjected to engineering modification on the basis of the wild type Rattus norveicus. Furthermore, the protein sequence of the gene is as shown in any one of SEQ No.1-55. In a rice genome site and a human HEK 293T cell genome site, the system shows efficient editing efficiency of a guide editor. The invention provides a series of efficient reverse transcriptase components which can be carried on a guide editing system, important bottom-layer technical support is provided for research of point mutation in a genome, creation of a special site disease model and correction of genetic mutation sites, and the reverse transcriptase component has a wide application prospect in the field of precision medicine and precision agriculture breeding.

The invention discloses construction and application of a Primrose syndrome non-human animal model, and belongs to the technical field of animal models and disease research. According to the invention, through a CRISPR / Cas9 technology, a codon CAC for coding 596th histidine in a No.14 exon of a mouse Zbtb20 gene is subjected to site-directed mutagenesis into CGC for coding arginine, and a hybrid mouse model for simulating pathogenic point mutation (p.H596R) of human Primrose syndrome is constructed. The model can stably reproduce key clinical phenotypes of the Primrose syndrome, including overgrowth after adult, serum IGF-1 rise, memory dysfunction and anxiety behaviors, and shows abnormal hippocampal neuronal development and synaptic transfer related pathways and the like. The invention provides an important experimental tool for deeply revealing the pathological mechanism of Primrose syndrome, developing drug screening and treatment intervention research and the like.

This invention relates to the fields of bioengineering and fermentation engineering, and discloses a genetically engineered *Streptomyces albopictus* strain that produces high levels of ε-polylysine and its fermentation production process. This genetically engineered strain uses *Streptomyces albopictus* strains acclimated to ε-polylysine tolerance as a chassis, and its genome integrates... ppc and dapf Through expression box, heterogeneous asd Expression cassettes, containing secretory signal peptides lysp Fusion expression cassettes and D404A / K499A point mutations pls Expression cassette. The fermentation process employs a two-stage pH control strategy, maintaining a neutral environment during the cell growth phase and adjusting to an acidic environment during product synthesis. This invention improves ε-polylysine yield through a synergistic strategy of enhancing precursor supply, constructing efflux detoxification channels, and increasing synthase activity; combined with an acidic fermentation process, it effectively inhibits product degradation, yielding a high-molecular-weight and highly uniform target product suitable for industrial production.

The invention discloses an organ-like drug resistance prediction method and device and a storage medium, and relates to the technical field of bioinformatics, and the method comprises the steps: S1, constructing an initial prediction model; s2, acquiring a training data set; s3, training an optimization prediction model; s4, acquiring related data of a to-be-predicted drug; s5, obtaining a prediction result of the drug resistance of the to-be-predicted drug; according to the method, the drug resistance of the organoid to the drug can be predicted more accurately. By fusing multi-dimensional features of gene mutation, target mutation and drug functional groups, the understanding and learning ability of the model to the drug resistance mechanism is enhanced, and the reliability of drug resistance prediction is improved. The method not only can accurately capture key information of influence of gene and target mutation on drug resistance, but also can highlight unique mutant genes of the organoid on drug resistance by comparing feature differences of the organoid and a common cell line, so that an efficient and accurate calculation framework is provided for drug resistance detection.

The application discloses a beta-1,4-xylanase mutant and a construction method thereof, and comprises the following steps: constructing a beta-1,4-xylanase recombinant expression vector; introducing the recombinant vector pNZ8048-P5-XynA into a competent lactococcus lactis by using an electrotransformation technology to construct a wild-type expression vector; on the basis, designing and constructing a multi-site mutant recombinant plasmid by using a site-directed mutation method, wherein the eighth asparagine (Asn) of the beta-1,4-xylanase is mutated into tyrosine (Tyr), the 22nd serine (Ser) is mutated into proline (Pro), and the 59th alanine (Ala) is mutated into lysine (Lys); introducing the multi-site mutant recombinant plasmid into the competent lactococcus lactis to construct a heterologous expression strain of the mutant beta-1,4-xylanase (Mut-1); and stably obtaining the mutant xylanase beta-1,4-xylanase (Mut-1) with high activity by using a metal affinity chromatography (Ni 2+ ) method. The specific enzyme activity of the mutant reaches 1929.30±5.36 U / mg, and the optimal temperature is increased by 15 DEG C compared with that of the wild type.

The invention discloses a genetic engineering strain of high-yield secondary metabolite Fumagillin as well as a construction method and application of the genetic engineering strain, and the genetic engineering strain is obtained by taking aspergillus fumigatus as a chassis bacterium through hosA gene knockout or hosA catalytic active site mutation. According to the method, a hosA gene knockout strain (delta hosA) and catalytic active site mutation strains (HosAD133A, HosAH175A and HosAD210A) are constructed by means of molecular biology, and the mutant strains are subjected to liquid or solid fermentation under the culture condition of 37 DEG C, so that the yield of Fumagillin can be remarkably increased. According to the method disclosed by the invention, the inhibition on a Fumagillin biosynthetic pathway is relieved and the metabolic flux is enhanced by utilizing the activity change of histone deacetylase caused by hosA defects, and an efficient and directional production method for high-yield Fumagillin is provided, so that the method has an important industrial application value.

The invention discloses a marine bacterium dextranase mutant and application thereof, and relates to the technical field of biology. The gene sequence of the mutant is as shown in SEQ ID NO. 1. The content of isomaltohexaose in a product of the mutant is high. According to the invention, sodium ion binding sites F269 and D273 are obtained through molecular docking of AIphiFlod3, and corresponding alanine site-directed mutants F269A and D273A are respectively constructed. The alanine without charges is selected as a substitution residue, so that steric hindrance is reduced, and the path of substrate entry and product release is optimized. F269 sensitive to sodium ions is preferably selected for saturation mutation, the optimal mutant F269G is obtained, and the number of hydrogen bonds between the optimal mutant F269G and the sodium ions is increased from 2 to 3. The side chain of glycine is a hydrogen atom and is an amino acid with the smallest side chain, so that the path of substrate entry and product release is optimized, and meanwhile, the thermal stability of the mutant is improved. The main product of the mutant F269G for hydrolyzing dextran T70 is isomaltohexaose with high polymerization degree.

The invention relates to the technical field of molecular biology and the technical field of gene editing, in particular to pegRNA of a specific target EGFR gene tyrosine 1068 site, a pilot editing system and application. The pegRNA comprises sgRNA (small guide RNA), sgRNA scaffold, an RT (reverse transcription) template and PBS (phosphate buffer solution); wherein the sequence of the pegRNA is as shown in SEQ ID NO. 1; the sequence of the sgRNA is as shown in SEQ ID NO. 2; the sequence of the sgRNA scaffold is as shown in SEQ ID NO. 3; the sequence of the RT template is as shown in SEQ ID NO. 4; the sequence of the PBS is as shown in SEQ ID NO. 5. The tyrosine 1068 site of the EGFR gene is mutated into phenylalanine, so that phosphorylation of the site is blocked, and a protein structure is maintained. The tyrosine 1068 site point mutant with the EGFR gene can be applied to research on preparation of drugs for treating cancers, research on drug resistance and research on screening of compounds of targeted EGFR signal channels.

The invention provides a construction method of a non-small cell lung cancer histone H1.3 arginine methylation point mutation cell model. The construction method comprises the following steps: designing mutation primers H1.3 R80A-F and H1.3 R80A-R; the method comprises the following steps: by taking a pCDH-HA-H1.3-Flag plasmid as a template, carrying out PCR (Polymerase Chain Reaction) amplification by adopting a mutation primer, digesting a product by DMT enzyme, and converting a competent cell to obtain a mutant plasmid; and co-transfecting the mutant plasmid and a helper plasmid to a packaging cell, collecting a virus solution, filtering, infecting an A549 cell, adding Polybrene to assist infection, culturing, and screening a stably transfected cell strain by using puromycin to obtain the recombinant plasmid. The invention also provides application of the mutant cell model obtained by the construction method. According to the invention, the blank of histone H1.3 methylation research is filled, the 80th arginine is clear as a core modification site, and the established model provides a new tool for lung cancer mechanism research and drug research and development.

The invention provides a molecular interaction network protection system based on structural biology and an optimization method thereof, and relates to the technical field of biotechnology and molecular engineering.The molecular interaction network protection system comprises a USAG-1 protein binding domain, and the USAG-1 protein binding domain comprises a Glu32-Arg58-Ser76 hydrogen bond network and a Phe41 / Trp65 / Leu83 hydrophobic core; the MMP-9 cleavage site mutant is used for carrying out 20 substitutions from D to N / V / A in the PLGLA sequence, and is combined with G52S mutation; the ellipticity of the CD spectrum of the RGD peptide at 222nm is less than or equal to-15 mdeg, and the RGD peptide comprises a salt bridge at the i / i + 4 position. The USAG-1 protein binding domain also comprises an Asn45 carbohydrate chain, and the molecular weight of the Asn45 carbohydrate chain is 500 to 2000 Da. The phi angle of the RGD peptide is-57 + / -5 degrees, and the psi angle of the RGD peptide is-47 + / -5 degrees. According to the invention, through a multi-dimensional structure locking strategy, while the functional activity of biomolecules is maintained, accurate control of alpha-helical conformation is realized, a resistance mutation library is constructed, and the fundamental contradiction of stability-activity imbalance, conformation control misalignment and single-point mutation drug resistance in the traditional technology is thoroughly solved.

The application relates to the field of biological medicine, and discloses a glucosyltransferase mutant, a coding gene of the glucosyltransferase mutant, a recombination carrier, a recombination strain, an enzyme preparation, and application of the glucosyltransferase mutant. The glucosyltransferase mutant is a point mutation at the R position of the amino acid sequence shown in SEQ ID NO:1, and 4-8 histidines are added at the N end. A method for preparing gastrodin comprises the following steps: contacting the glucosyltransferase mutant with p-hydroxybenzyl alcohol and uridine diphosphate glucose. The glucosyltransferase mutant provided by the application has higher specificity for the substrate p-hydroxybenzyl alcohol, thereby obviously improving the conversion rate of the conversion of p-hydroxybenzyl alcohol into gastrodin, and having a good industrial application prospect.

The invention discloses a phytase mutant with improved enzymatic activity and thermal stability as well as a preparation method and application thereof, and relates to the technical field of gene engineering and enzyme engineering. The amino acid sequence of the phytase mutant (named as Y111C / Q113L) is as shown in SEQ ID NO. 1. According to the invention, site-directed mutagenesis is carried out on amino acid residues which may influence the enzymatic activity and thermal stability of phytase YrAPPA in phytase YrAPPA, and mutants Y111C and Q113L with significantly improved enzymatic activity and thermal stability are constructed and screened. On the basis, the two-site mutant Y111C / Q113L with the phytase activity and the thermal stability further improved is further constructed and obtained. The enzyme activity and thermal stability of the phytase mutant provided by the invention are obviously improved, and the phytase mutant has a good application prospect in the field of animal feed additives.

The present application relates to the field of bioengineering, and particularly to a mutant of an enzyme, a mutant of a glycosyltransferase and application thereof in preparing rhodiolin. The present application provides a mutant of an enzyme, which has the following amino acid site mutations on the basis of a wild-type glycosyltransferase: the 308th site is mutated from I to Q, the 333rd site is mutated from V to R, the 363rd site is mutated from W to S and the 386th site is mutated from S to G, and the amino acid sequence of the wild-type glycosyltransferase is shown as SEQ ID NO: 1. The present application obtains a glycosyltransferase and a sucrose synthase with improved thermal stability through structural rational design and deep learning modification, and can glycosylate tyramine to generate rhodiolin in the form of regenerating ADP-glucose, and the price of ADP is only about 20% of UDP, which has a cost advantage.

The invention discloses a preparation for treating erectile dysfunction caused by diabetes as well as a preparation method and application of the preparation. The invention firstly finds that a palmitoylation modification site, namely a 282 site, exists beside a 260 site in an Fbp1 functional region, and the site can be modified by the palmitoylation site to cause Fbp1 function damage. Therefore, point mutation modified Fbp1 mRNA of a C282S site is found and synthesized for the first time, namely cysteine of a 282 site is converted into serine, so that the Fbp1 is not subjected to Zdhhc13 palmitoylation modification and further is not subjected to function damage, lipid nanoparticles capable of targeted delivery of the modified Fbp1 mRNA are synthesized, and the C282S-Fbp1 mRNA loaded by the nanoparticles is infiltrated into a mouse cavernous body, so that the number of the Fbp1 is recovered, and the activity of the C282S-Fbp1 is improved. Therefore, the lactic acid concentration of the DMED penis cavernosum is effectively reduced, and the erectile function of a DMED mouse is remarkably improved.

The invention discloses a high-efficiency PET hydrolase mutant and an application of the high-efficiency PET hydrolase mutant in PET plastic degradation. The PET hydrolase is characterized in that the PET hydrolase is a protein of the following (a) or (b): (a) a protein as shown in SEQ ID NO.1; and (b) a protein which is derived from (a) by substituting, deleting or adding one or more amino acids in the amino acid sequence in (a), has hydrolase activity and is derived from (a). The high-yield PET hydrolase ClbPETase (the expression quantity is 80 mg / L) is excavated from an environmental metagenome through an HMM method, and the high-yield PET hydrolase ClbPETase has great industrial application potential. A plurality of single-point mutants and a series of combined mutants are constructed through a rational design method assisted by machine learning, a mutant UltraPETase with the optimal catalytic performance is obtained through superposition of single-point mutation, complete depolymerization of PET powder can be achieved by reacting for 8 hours at the temperature of 65 DEG C or reacting for 6 hours at the temperature of 60 DEG C. And a novel efficient depolymerization enzyme resource is provided for biological enzyme depolymerization of polyester plastics.

The application belongs to the field of bioengineering. The application provides a molecular modification design method for improving the hydrophobicity of the catalytic center of bacillus subtilis protease, which comprises the following steps: searching for a resolved bacillus subtilis protease crystal structure in a protein database PDB, generating an enzyme-substrate complex by docking a hexapeptide substrate through a Glide mode of software, calculating the polar charge of each amino acid residue of polar atoms N and O and H combined thereof within a 10 angstrom range of the catalytic center amino acid of the bacillus subtilis protease by using a PPC force field, calculating the absolute value sum of the polar charge, selecting a potential mutation site of the bacillus subtilis protease, virtually mutating the potential mutation site into a large steric hindrance nonpolar amino acid, calculating the absolute value sum of the polar charge of polar atoms N, O and H within a 10 angstrom range of the catalytic center amino acid of the single-point mutant by using the PPC force field, selecting a virtual bacillus subtilis protease single-point mutant, expressing the mutant and iteratively mutating, re-expressing, obtaining a modified bacillus subtilis protease mutant, and verifying the hydrophobicity. The molecular modification design method can quickly and effectively reduce water molecules in the catalytic center of the bacillus subtilis protease and improve the hydrophobicity thereof. It has been verified that the enzyme modification method is effective and reliable.

The invention discloses a method for improving the water-resistant straw-like dwarf virus capability of rice based on D14 protein site editing and application of the method, according to the scheme, an interaction interface of RGSV P3 and rice D14 protein is analyzed through a structural biology means, and it is determined that the 102nd part, with the D14 binding site, of D14 and P3 is aspartic acid (Asp, D). Then, accurate editing of the D14 gene in the rice is realized by utilizing a cytidine base editor (CBE) system, and the site is mutated into asparagine (Asn, N), so that D14 (D102N) transgenic rice is obtained. Disease resistance identification confirms that the mutant has significant resistance to RGSV. Furthermore, a homozygous non-transgenic disease-resistant material which does not contain exogenous transgenic ingredients is obtained through genetic screening and has a good breeding application prospect.

The present application relates to the field of biotechnology and enzyme engineering, and particularly relates to a lipase mutant expressed in Escherichia coli and application thereof. Specifically, in order to solve the technical problem that the catalytic activity of the existing Rhizopus oryzae lipase (ROL) is insufficient and it is difficult to meet the needs of industrial production, the purpose of the present application is to provide a lipase variant with significantly improved catalytic activity and / or thermal stability. On the basis of the existing ROL four-point mutant ROL-E190C / V209L / E238C / D262G (the amino acid sequence is shown as SEQ ID NO. 1), the present application innovatively introduces a machine learning assisted design strategy, and through multiple rounds of 'prediction-verification-model optimization' iteration cycles, a series of excellent lipase mutants are successfully obtained.

This invention discloses a nicotinamide phosphoribosyltransferase mutant, a recombinant strain, and a method for constructing the same. The mutants are I457V, G344A, Q378A, T283G, or F182A, obtained by single-point mutation of the wild-type nicotinamide phosphoribosyltransferase shown in SEQ ID NO:1. This invention utilizes a method derived from... Schizotequatrovirus By rationally designing and site-directed mutagenesis of KVP40 nicotinamide phosphoribosyltransferase, combined with metabolic engineering to block the NMN degradation pathway and enhance substrate synthesis and product transport, the yield of β-NMN by the recombinant strain during shake-flask fermentation reached 4.82 g / L. Through optimization of fed-batch fermentation conditions, the highest yield of β-NMN during fed-batch fermentation in shake flasks reached 15.60 g / L.

The invention relates to an antibacterial peptide as well as a carrier and application thereof. The antibacterial peptide comprises a first polypeptide and a cell-penetrating peptide which are connected, the first polypeptide is obtained by mutating amino acid at the No.19 site of an original peptide, and the nucleotide sequence of the original peptide is as shown in SEQ ID NO.2. The brand new chimeric antibacterial peptide KLA-19A is constructed through strategies such as truncation transformation, website prediction, cell-penetrating peptide connection, point mutation and the like by taking an antibacterial peptide Astrucin as a template and is used for researching antibacterial activity, and the chimeric antibacterial peptide has broad-spectrum antibacterial activity and low cytotoxicity.