An antimicrobial peptide and its application in the preparation of antimicrobial drugs

Abstract

This invention discloses an antimicrobial peptide YKL19 and its application in the preparation of antimicrobial drugs, belonging to the field of biomedical technology. The amino acid sequence of this antimicrobial peptide is shown in SEQ ID NO:1. YKL19 exhibits excellent antimicrobial activity against a variety of standard strains and clinically resistant strains. Simultaneously, YKL19 possesses comprehensive advantages such as rapid and sustained bactericidal action, low hemolytic activity, low likelihood of inducing drug resistance, and good stability in human plasma. The antimicrobial peptide YKL19 provided by this invention has broad industrial application prospects in the preparation of antimicrobial drugs, cosmetics, health product additives, and animal feed additives.

Description

Technical Field

[0001] This invention belongs to the field of biomedical technology, specifically relating to a novel antimicrobial peptide YKL19 and its application in the preparation of antimicrobial drugs. Background Technology

[0002] Traditional small-molecule antibiotics exert their bactericidal effects primarily by acting on specific biological targets in bacteria (such as cell wall synthases, ribosomal subunits, and nucleic acid synthases). Due to their singular mechanism of action, bacteria can rapidly develop resistance through various pathways, including target gene mutations, the production of inactivating enzymes, active drug efflux, and biofilm formation, leading to clinical failure of anti-infective treatments. Current strategies for addressing antibiotic resistance include: structural modification of existing antibiotics, the use of multiple antibiotic combinations, the development of phage therapy, and the research and development of antimicrobial peptides and other novel antimicrobial materials. However, structural modification of existing antibiotics easily leads to cross-resistance, and research and development efficiency continues to decline; combination therapy increases the risk of drug toxicity and may induce multidrug resistance in bacteria; phage therapy has limitations such as a narrow host spectrum, poor in vivo stability, and a tendency to trigger immune responses; while existing natural antimicrobial peptides generally suffer from high hemolytic toxicity, poor protease stability, and high costs associated with large-scale production.

[0003] Antimicrobial peptides (AMPs) are naturally occurring immunomodulatory molecules formed during long-term biological evolution. As key mediators of the host's natural immune system, they play a central role in resisting pathogen invasion and are hailed as "natural antibacterial agents." These substances typically consist of no more than 50 amino acid residues, exhibiting typical amphiphilic structural characteristics and carrying a net positive charge of +2 to +9 under physiological conditions. Based on their spatial conformational differences, antimicrobial peptides can be mainly classified into four categories: α-helical linear peptides, β-sheet peptides, cyclic peptides, and flexible peptides.

[0004] The antibacterial mechanisms of antimicrobial peptides are unique and complex, differing from the single-target action mode of traditional small-molecule antibiotics. Their primary target is the bacterial cell membrane, and reported membrane perturbation mechanisms include: insertion into the cell membrane to form micelle structures, parallel binding to the membrane surface to distort the polar arrangement of lipids, and formation of ring-shaped ion channels perpendicular to the membrane. In addition to membrane action mechanisms, some antimicrobial peptides can also penetrate the cell membrane and enter the cell to exert their bactericidal effects by binding to nucleic acids, inhibiting protein synthesis, or interfering with enzyme activity.

[0005] Antimicrobial peptides possess broad-spectrum biological activity, exhibiting significant inhibitory effects against both Gram-positive and Gram-negative bacteria. They also act on fungi, enveloped viruses, and even some cancer cells, while simultaneously possessing multiple biological functions such as immunomodulation, wound healing promotion, and inflammatory response regulation. Compared to traditional small-molecule antibiotics, antimicrobial peptides offer significant advantages, including rapid bactericidal action, diverse anti-infection mechanisms, and a lower likelihood of inducing bacterial resistance. They can also effectively inhibit common multidrug-resistant strains, making them highly promising antibiotic alternatives. Summary of the Invention

[0006] In view of the numerous shortcomings of the existing technologies, this invention aims to provide a novel antimicrobial peptide, YKL19, and its applications to address the industry's technical pain points, such as high incidence of drug resistance, poor biosafety, insufficient body fluid stability, and limited applicable scenarios of existing clinical antimicrobial drugs. The novel antimicrobial peptide YKL19 provided by this invention not only possesses excellent broad-spectrum antimicrobial activity, exhibiting highly effective inhibition and killing effects against a variety of common clinical pathogens and drug-resistant strains, but also boasts multiple superior characteristics, including extremely low hemolytic activity, low likelihood of inducing bacterial resistance, excellent stability in the human plasma environment, and good biocompatibility. It can effectively overcome the technical shortcomings of traditional small-molecule antibiotics and existing natural antimicrobial peptides, providing a new, safe, and stable technical solution for the treatment of drug-resistant bacterial infections and antibacterial applications in multiple fields.

[0007] To achieve the above objectives, the present invention provides the following complete technical solution: In a first aspect, the present invention provides a novel antimicrobial peptide YKL19, the amino acid sequence of which is shown in SEQ ID NO.1.

[0008] Preferably, the antimicrobial peptide YKL19 is an artificially optimized short-chain antimicrobial peptide. Compared with natural antimicrobial peptides, its amino acid sequence is more concise and its structural stability is stronger. It can effectively reduce the degradation efficiency of proteases and further improve the antibacterial stability in vivo and in vitro.

[0009] Optionally, the antimicrobial peptide YKL19 can be prepared by any conventional method in the art, such as chemical solid-phase synthesis or microbial recombinant expression. The preparation process is simple, suitable for large-scale mass production, and the production cost is controllable, thus having good prospects for industrial application.

[0010] Secondly, the present invention provides a nucleic acid molecule encoding the aforementioned antimicrobial peptide YKL19.

[0011] Furthermore, the nucleic acid molecule is an optimized coding sequence adapted to prokaryotic or eukaryotic expression systems, capable of accurately encoding the amino acid sequence of the antimicrobial peptide YKL19 as shown in SEQ ID NO.1.

[0012] Preferably, the nucleic acid molecule is optimized for codon preference and can be adapted to the expression systems of commonly used host cells such as Escherichia coli and yeast, significantly improving the recombinant expression efficiency and yield of the antimicrobial peptide YKL19.

[0013] Thirdly, the present invention provides a recombinant expression vector comprising the above-mentioned nucleic acid molecule encoding the antimicrobial peptide YKL19.

[0014] Furthermore, the recombinant expression vector is a conventional prokaryotic or eukaryotic expression vector in the art, including but not limited to pET series vectors, pGEX series vectors, pPIC9K yeast expression vector, etc.

[0015] Preferably, the recombinant expression vector contains complete functional elements such as a promoter, terminator, resistance selection marker, and origin of replication, which can realize the stable replication, efficient transcription and translation expression of nucleic acid molecules in host cells.

[0016] Optionally, the recombinant expression vector may be fitted with a tag protein coding sequence as needed to facilitate the subsequent isolation, purification, and activity detection of the antimicrobial peptide.

[0017] Fourthly, the present invention provides a recombinant host cell comprising the above-described recombinant expression vector.

[0018] Furthermore, the recombinant host cell is a prokaryotic host cell or a eukaryotic host cell.

[0019] Preferably, the prokaryotic host cells include engineered strains such as Escherichia coli BL21 and DH5α, and the eukaryotic host cells include model strains such as Pichia pastoris and Saccharomyces cerevisiae. The above-mentioned host cells have a fast proliferation rate, low culture cost, and no risk of endotoxin contamination, making them suitable for large-scale industrial expression and production.

[0020] Optionally, the recombinant host cells can be stably passaged under conventional aseptic culture conditions and can continuously and efficiently express the antimicrobial peptide YKL19, exhibiting stable characteristics and being resistant to degradation.

[0021] Fifthly, the present invention provides an antibacterial composition, wherein the antibacterial composition uses the above-mentioned antimicrobial peptide YKL19 as the core active antibacterial component, and also contains a pharmaceutically acceptable carrier or excipient.

[0022] Furthermore, the pharmaceutically acceptable carrier or excipient includes, but is not limited to, one or more of diluents, stabilizers, excipients, disintegrants, lubricants, solvents, and sustained-release materials, which can be rationally proportioned according to the dosage form requirements.

[0023] Preferably, the antibacterial composition can be prepared into various commonly used pharmaceutical dosage forms such as injections, tablets, capsules, ointments, sprays, and sustained-release formulations, to suit different routes of administration and application scenarios.

[0024] Optionally, other natural antibacterial and anti-inflammatory components may be added to the antibacterial composition to form a synergistic antibacterial and anti-inflammatory effect with the antimicrobial peptide YKL19, further enhancing the overall efficacy of the composition.

[0025] In a sixth aspect, the present invention provides the use of the above-mentioned antimicrobial peptide YKL19, or an antimicrobial composition containing the antimicrobial peptide, in the preparation of antimicrobial drugs.

[0026] Preferably, the pathogenic bacteria include, but are not limited to, one or more of Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Porphyromonas gingivalis, covering clinically common Gram-positive and Gram-negative bacteria.

[0027] Furthermore, the pathogens also include clinically isolated drug-resistant strains resistant to traditional antibiotics such as penicillin, cephalosporins, quinolones, and carbapenems, which can effectively solve the problem of difficult-to-treat and easy-to-relapse infections caused by multidrug-resistant bacteria in clinical practice.

[0028] Optionally, the antibacterial drug can be used to treat a variety of clinical infectious diseases, such as skin and soft tissue infections, respiratory tract infections, urinary tract infections, oral and periodontal infections, and wound infections.

[0029] In a seventh aspect, the present invention provides the application of the above-mentioned antimicrobial peptide YKL19 in the preparation of antibacterial or bactericidal products.

[0030] Furthermore, the products include, but are not limited to, medical antibacterial products, daily cosmetics, antibacterial additives for health products, and feed additives for livestock, poultry, and aquatic animals.

[0031] Preferably, the antimicrobial peptide YKL19, with its low hemolysis, high safety, and good stability, can replace traditional chemical antibacterial agents and be used in mild skin care cosmetics, food-grade health product additives, and green antibiotic-free animal feed, with higher safety and no residual pollution.

[0032] Optionally, the antibacterial or bactericidal product can be prepared in various forms such as solution, powder, ointment, and spray, to suit different application scenarios such as medical disinfection, daily protection, and aquaculture antibacterial, and has a wide range of applications.

[0033] Eighthly, the present invention provides the use of the above-mentioned antimicrobial peptide YKL19, or an antimicrobial composition containing the antimicrobial peptide, in antimicrobial or bactericidal activities for non-disease treatment purposes, wherein the antimicrobial or bactericidal target is bacteria.

[0034] Preferably, in any of the foregoing embodiments, the antibacterial properties include bacteriostasis or bactericidal effects.

[0035] The antimicrobial peptide YKL19 provided by this invention possesses comprehensive advantages such as broad-spectrum antibacterial activity, low hemolytic activity, low susceptibility to inducing drug resistance, and good stability in human plasma. It can be used to prepare antimicrobial drugs for treating infections caused by common sensitive or drug-resistant bacteria in clinical practice. Simultaneously, YKL19 can also be used as a preservative in cosmetics and health product additives, as well as in animal feed additives for preservation and treatment of bacterial infections in animals. It can also be used as an experimental drug, such as a positive control in experiments, demonstrating broad prospects for industrial application.

[0036] The novel antimicrobial peptide YKL19 provided by this invention has the following beneficial effects: (1) Broad-spectrum antibacterial activity: YKL19 showed excellent antibacterial activity against a variety of standard strains and clinically resistant strains. The MIC values ​​against standard strains were between 8 and 32 μg / mL, and the MIC values ​​against clinically resistant strains were between 8 and 16 μg / mL. The antibacterial spectrum covered Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli and Porphyromonas gingivalis, etc.

[0037] (2) Fast and long-lasting bactericidal effect: At the MIC concentration, YKL19 can kill all Escherichia coli within 2 hours, and no bacteria will recover and grow until 18 hours. The duration of bactericidal effect is significantly better than that of polymyxin E control.

[0038] (3) Low hemolytic activity: The hemolytic value HC50 of YKL19 is greater than 128 μg / mL, indicating that it has low toxicity to mammalian erythrocytes and good safety.

[0039] (4) Difficult to induce drug resistance: After 30 generations of continuous induction with YKL19 at 1 / 2 MIC concentration, Escherichia coli still did not develop drug resistance; while the MIC value of the control antibiotic norfloxacin increased 16 times after 17 consecutive passages and 128 times after 28 passages.

[0040] (5) Good stability in human plasma: After incubation in human plasma for 3 hours and 6 hours, the MIC of YKL19 was 16 and 32 μg / mL, respectively, with little change in antibacterial activity, indicating that it has good stability in human plasma environment. Attached Figure Description

[0041] Figure 1 The image shows the time-bactericidal curve of the antimicrobial peptide YKL19 of this invention against Escherichia coli ATCC 25922, with the horizontal axis representing time (h).

[0042] Figure 2The graph shows the hemolysis rate of the antimicrobial peptide YKL19 at different concentrations. The horizontal axis represents the antimicrobial peptide at different concentrations (16~128μg / mL), the positive control X-100, and the negative control PBS.

[0043] Figure 3 This is a graph showing the results of the drug resistance induction experiment of the antimicrobial peptide YKL19 of this invention against Escherichia coli ATCC 25922. The horizontal axis represents the number of passages, and the vertical axis represents the minimum molecular weight (MIC). n MIC0 is the minimum inhibitory concentration after n passages, and MIC0 is the minimum inhibitory concentration in the 0th generation (the original strain has not been passaged under drug pressure). Detailed Implementation

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0046] Example 1: Synthesis and Identification of Antimicrobial Peptide YKL19 The antimicrobial peptide YKL19 was synthesized by Hefei Hesheng Biotechnology Co., Ltd., with a purity of 96.94%.

[0047] The amino acid sequence of YKL19 is shown in SEQ ID NO.1.

[0048] SEQ ID NO.1 YKAAVKKLVRGIKRVLKGL.

[0049] Example 2: Determination of the minimum inhibitory concentration (MIC) of the antimicrobial peptide YKL19 1. Experimental strain Standard strains: Staphylococcus aureus ATCC 29213, Acinetobacter baumannii ATCC 19606, Klebsiella quasipneumoniae ATCC 700603, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, and Porphyromonas gingivalis ATCC 33277.

[0050] Clinically resistant strains: Klebsiella pneumoniae 418015, Escherichia coli 103231, Pseudomonas aeruginosa 304238, and Acinetobacter baumannii 316039, all provided by the Microbiology Laboratory of the Clinical Laboratory Department, and their drug susceptibility results are shown in Table 1. The drug susceptibility results showed that these clinical isolates exhibited resistance (R) to multiple antibiotics, including ticarcillin / clavulanic acid, piperacillin / tazobactam, ceftazidime, cefoxitin, ceftriaxone, doxycycline, and polymyxin E, thus constituting multidrug-resistant strains.

[0051] Table 1. Antimicrobial susceptibility results of clinical strains R: Resistance; S: Sensitivity; I: Intermediate; ND: Not detected 2. MIC determination method The MIC assay was performed using the microbroth dilution method, following the guidelines established by the Clinical and Laboratory Standards Institute (CLSI) in the United States.

[0052] The specific procedures are as follows: First, dissolve the antimicrobial peptide in sterile distilled water to prepare an initial stock solution of 5120 μg / mL, and store it at 4°C. Before use, dilute the stock solution to 512 μg / mL with cationic-adjusted Mueller-Hinton broth (CAMHB), and then perform serial dilutions of 2-fold in 96-well plates. Adjust the bacterial culture medium to a McFarland concentration of 0.5, dilute it 100-fold with fresh CAMHB, and add 100 μL to the 96-well plate containing the antimicrobial peptide to achieve a final bacterial concentration of 5 × 10⁻⁶. 5 CFU / mL. After incubating the 96-well plate at 37°C for 16-20 hours, the lowest concentration of antimicrobial peptide at which no obvious bacterial growth is observed with the naked eye is taken as the MIC value.

[0053] MIC determination of *Porphyromonas gingivalis*: The peptide was dissolved in sterile distilled water to prepare a stock solution with a concentration of not less than 2560 μg / mL, aliquoted, and stored at -80°C. On the day of the experiment, the stock solution was diluted 10-fold with Wilkins-Chalgren broth to the required highest concentration, followed by serial dilutions of 2-fold in 96-well plates. After reviving the *Porphyromonas gingivalis* standard strain ATCC 33277, single colonies were picked and cultured to the logarithmic growth phase. After centrifugation and washing, the bacterial culture was adjusted to a McFarland concentration of 0.5 using a turbidimeter, and then diluted 100-fold with fresh broth to obtain approximately 1 × 10⁻⁶ μg / mL. 6 Working bacterial culture at CFU / mL. Add 100 μL to a 96-well plate containing the peptide to achieve a final bacterial concentration of 5 × 10⁻⁶. 5 CFU / mL. After placing the 96-well plate in an anaerobic bag and incubating for 48 hours, the lowest peptide concentration at which no obvious bacterial growth is observed with the naked eye is taken as the MIC value.

[0054] 3. MIC Measurement Results The antibacterial activity of YKL19 against six standard strains is shown in Table 2. The results showed that the MICs of YKL19 against standard Klebsiella pneumoniae (ATCC 700603), Acinetobacter baumannii (ATCC 19606), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (ATCC 25922) were all between 8 and 32 μg / mL.

[0055] The antibacterial activity of YKL19 against clinically resistant strains is shown in Table 3. The results indicate that YKL19 also exhibits good antibacterial activity against resistant bacteria, with MICs ranging from 8 to 16 μg / mL.

[0056] Table 2. Antimicrobial activity of antimicrobial peptide YKL19 against five standard bacterial strains. MIC: Minimum inhibitory concentration; a: Staphylococcus aureus; b: Acinetobacter baumannii; c: Klebsiella pneumoniae; d: Pseudomonas aeruginosa; e: Escherichia coli; f: Porphyromonas gingivalis; Quality control results showed that the growth control wells were all turbid, while the blank control wells were all clear.

[0057] Table 3. Antimicrobial activity of antimicrobial peptide YKL19 against clinically resistant strains Example 3: Determination of the time-based bactericidal curve of antimicrobial peptide YKL19 Overnight culture of *E. coli* (ATCC 25922) was adjusted to a McFarland concentration of 0.5, diluted 100-fold with fresh CAMHB medium, and incubated at 37°C and 150 rpm for 3.5 hours to reach the logarithmic growth phase. Two shake tubes were then filled with 10 mL of 4×MIC polymyxin E (2 μg / mL) and antimicrobial peptide YKL19 (32 μg / mL, both dissolved in CAMHB medium), respectively. Another shake tube was filled with 10 mL of CAMHB medium. The *E. coli* culture in the logarithmic growth phase was adjusted to 1 MCF, diluted 100-fold, and added to the three shake tubes to achieve a final concentration of 3×10⁻⁶. 6 CFU / mL, and incubated at 37℃ and 150 rpm. At 0, 2, 4, 6, 18 and 24 hours after adding the bacterial solution, 200 μL of each group of bacterial solution was taken and serially diluted 10-fold with CAMHB medium, and 10 μL was dropped onto Mueller-Hinton agar (MHA) plates. After drying, the plates were incubated upside down at 37℃ for 24 hours and the results were read.

[0058] The results show (see) Figure 1 YKL19 at a concentration of 4×MIC can kill all E. coli within 2 hours, and no E. coli can revive until 18 hours. While polymyxin E at a concentration of 4×MIC can exert a rapid bactericidal effect within 2 hours, bacteria gradually revive after 8 hours of co-incubation, and the bacterial concentration at 18 hours is comparable to the blank control group. This indicates that YKL19 has a similar bactericidal rate to polymyxin E against E. coli, but a longer duration of action.

[0059] Example 4: Determination of hemolytic activity of antimicrobial peptide YKL19 Defibrinated rabbit red blood cells (RBCs) were washed three times with sterile PBS buffer and then added to 96-well U-shaped plates containing different concentrations of antimicrobial peptides, achieving an RBC concentration of 2% (v / v) and an antimicrobial peptide concentration ranging from 16 to 128 μg / mL, with a final volume of 200 μL per well. Negative and positive controls were included: RBCs treated with PBS alone served as the negative control, and RBCs treated with 0.5% Triton X-100 served as the positive control. After incubating the 96-well plates at 37°C for 1 hour, the plates were centrifuged at 4°C and 1200g for 15 minutes. The supernatant was collected and transferred to a new flat-bottomed 96-well plate, and the absorbance at OD570 nm was measured. The hemolysis rate was calculated using the following formula: The results are as follows Figure 2 As shown, the hemolysis value (HC50) of YKL19 is greater than 128 μg / mL, indicating a low hemolysis rate and low toxicity to mammalian erythrocytes, suggesting good safety.

[0060] Example 5: Induction of drug resistance by antimicrobial peptide YKL19 Antimicrobial peptides exert their antibacterial effects primarily by disrupting bacterial cell membranes. Their mechanism of action is not limited to specific targets, thus reducing the likelihood of bacterial resistance. Bacteria in the logarithmic growth phase were adjusted to a 0.5 McFarland concentration using CAMHB medium. After a 100-fold dilution with fresh CAMHB, the diluted culture was added to 96-well plates containing gradient concentrations of antimicrobial peptides. After 18 hours of static incubation, the MIC values ​​were measured. After 24 hours of incubation, bacterial cultures still growing in the wells with the highest drug concentration were taken, diluted 1:10000 with fresh CAMHB medium, and added to new 96-well plates containing gradient concentrations of antimicrobial peptides. After 18 hours of incubation, the second-generation MIC values ​​were measured. Subsequent passages were performed every 24 hours using the same method, for a total of 30 passages, with dynamic monitoring of MIC value changes.

[0061] The results are as follows Figure 3 As shown, after 30 consecutive passages of the antimicrobial peptide YKL19 at a concentration of 1 / 2 MIC, no resistance was developed in *E. coli*. In contrast, the MIC value of the control antibiotic norfloxacin increased 16-fold after 17 passages and reached 128-fold after 28 passages, indicating significant resistance in *E. coli* to norfloxacin. Therefore, the antimicrobial peptide YKL19 can effectively prevent the development of bacterial resistance.

[0062] Example 6: Human plasma stability test of antimicrobial peptide YKL19 Using human plasma as the dilution medium, the 5120 μg / mL antimicrobial peptide stock solution was diluted to 256 μg / mL, followed by a two-fold serial dilution in 96-well plates to ensure each well contained 50 μL of antimicrobial peptide at concentrations ranging from 0.063 to 128 μg / mL. After incubating the 96-well plates at 37°C for 0, 3, and 6 hours, 150 μL of bacterial culture (adjusted to 0.5 McFarland concentration with CAMHB and then diluted 1:150) was added to each well. After incubation at 37°C for 18 hours, bacterial growth was recorded in each well to assess the stability of the antimicrobial peptide in human plasma.

[0063] The results are shown in Table 4.

[0064] Table 4. Changes in the antibacterial activity of YKL19 against Escherichia coli ATCC 25922 after co-incubation with human plasma for different time periods. The results showed that after co-incubation with plasma for 3 and 6 hours, the MICs of YKL19 were 16 and 32 μg / mL, respectively, with little change in antibacterial activity, suggesting that the antimicrobial peptide has acceptable stability in human plasma.

[0065] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to the above embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An antimicrobial peptide, characterized in that, The amino acid sequence of the antimicrobial peptide is shown in SEQ ID NO.

1.

2. A nucleic acid molecule encoding an antimicrobial peptide, characterized in that, The nucleic acid molecule encodes the antimicrobial peptide of claim 1.

3. A recombinant expression vector for expressing antimicrobial peptides, characterized in that, The recombinant expression vector comprises the nucleic acid molecule as described in claim 2.

4. A recombinant host cell expressing an antimicrobial peptide, characterized in that, The recombinant host cell comprises the recombinant expression vector of claim 3.

5. A bacteriostatic or bactericidal composition, characterized in that, It contains the antimicrobial peptide of claim 1 as the active ingredient, and a pharmaceutically acceptable carrier or excipient.

6. The composition according to claim 5, characterized in that, The composition is prepared as an injection, tablet, capsule, ointment, or spray formulation.

7. The composition according to claim 5, characterized in that, The composition is prepared as a sustained-release formulation.

8. The use of the antimicrobial peptide of claim 1 or the composition of claim 5 in the preparation of antibacterial or bactericidal products, characterized in that, The target of the antibacterial or bactericidal action is bacteria.

9. The use of the antimicrobial peptide of claim 1 or the composition of claim 5 in antibacterial or bactericidal effects for non-disease treatment purposes, characterized in that, The target of the antibacterial or bactericidal action is bacteria.

10. The application according to claim 8 or claim 9, characterized in that, The bacteria include one or more of Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Porphyromonas gingivalis.

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