An antimicrobial peptide AI18 and its application

Abstract

This invention discloses an antimicrobial peptide AI18 and its applications, belonging to the field of biotechnology. The amino acid sequence of the antimicrobial peptide AI18 is shown in SEQ ID NO.1, with its C-terminus after amidation. The antimicrobial peptide AI18 provided by this invention exhibits broad-spectrum antimicrobial activity, particularly showing significant inhibitory effects against Gram-negative, drug-resistant, and non-drug-resistant bacteria. Animal model experiments demonstrate that the antimicrobial peptide AI18 possesses good in vivo antimicrobial activity. The antimicrobial peptide AI18 can exist relatively stably in plasma with extremely low hemolytic activity and good biosafety, making it suitable for the treatment of bacterial infections and other applications requiring sterilization or inhibition of bacterial growth. The antimicrobial peptide AI18 provided by this invention has a short sequence, small molecular weight, and low chemical synthesis difficulty, thus saving on large-scale production costs.

Description

Technical Field

[0001] This invention relates to the field of biotechnology, specifically to an antimicrobial peptide AI18 with high antimicrobial activity and its applications. Background Technology

[0002] In recent years, the overuse of antibiotics has led to a series of problems, including the emergence of a large number of drug-resistant strains and a decline in the efficacy of antibiotics, seriously threatening the health of humans and animals. As a potential alternative to antibiotics, antimicrobial peptides (AMPs) have broad-spectrum antibacterial activity and also have inhibitory and killing effects on some viruses, parasites, and tumor cells. Moreover, they are less likely to induce drug resistance and have promising application prospects in medical, veterinary, and life science research fields.

[0003] Antimicrobial peptides (AMPs) are a class of basic polypeptides with antimicrobial activity that are induced to be produced in vivo. They are an important component of the innate immune system of organisms, with molecular weights ranging from 2000 to 7000 and composed of 20 to 60 amino acid residues. Most of these active polypeptides exhibit strong alkalinity, thermal stability, and broad-spectrum antimicrobial activity. Since the 1970s, researchers have discovered similar antimicrobial polypeptides in insects, crustaceans, mollusks, amphibians, mammals, humans, and plants. Data shows that, to date, more than 2000 AMPs have been reported in the literature.

[0004] However, compared to antibiotics, antimicrobial peptides have limitations such as lower antimicrobial activity, uncertain toxicity characteristics, and susceptibility to inactivation during production and transportation, hindering their widespread application. To address these challenges, current research focuses on developing antimicrobial peptides with enhanced activity, reduced toxicity, and improved hydrolysis resistance. In recent years, researchers have used software-assisted technologies such as computer bioinformatics prediction to design and optimize antimicrobial protein coding sequences, obtaining a series of modified recombinant antimicrobial peptides / proteins. To address issues such as the spatial instability of some AMPs and their hemolytic activity, researchers have attempted to enhance their antimicrobial activity and reduce their immune response by replacing some amino acids within the AMP molecule and modifying its molecular structure.

[0005] For example, patent document CN111925430A discloses a rational molecular design for the antimicrobial peptide Pexiganan derived from the epithelium of the African clawed frog. This design includes increasing the number of positively charged amino acids, increasing the proportion of hydrophobic amino acids, increasing the proportion of α-helices, and appropriately introducing non-natural amino acids (such as ornithine) and D-type amino acids. This optimized antimicrobial peptide improves the antibacterial effect to a certain extent and reduces the hemolysis rate and cytotoxicity.

[0006] Currently, most research on antimicrobial peptides remains in the preclinical stage, with relatively few drug-grade antimicrobial peptides. Despite significant efforts, only about 80 peptide drugs have received regulatory approval, indicating that treatment-relevant antimicrobial peptides are sparsely distributed across this vast sequence space. Therefore, the development of antimicrobial peptides with high antimicrobial activity and minimal side effects is urgently needed. Summary of the Invention

[0007] The purpose of this invention is to provide a new antimicrobial peptide with strong antibacterial activity, simple structure, and good biosafety.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention designs an antimicrobial peptide AI18 using artificial intelligence technology. Its amino acid sequence is shown in SEQ ID NO.1, and its C-terminus is amidated.

[0010] Specifically, the sequence of the antimicrobial peptide AI18 is: Ala-Ile-Pro-Lys-Arg-Leu-Arg-Arg-Phe-Tyr-Leu-Arg-Ala-Leu-Ala-Arg-Arg-Leu-NH2.

[0011] In this invention, the antimicrobial peptide AI18 can be prepared by chemical synthesis or genetic engineering.

[0012] This invention provides the use of the antimicrobial peptide AI18 in the preparation of antimicrobial drugs.

[0013] Furthermore, the antibacterial drug is an inhibitor of Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, Propionibacterium acnes, or Enterococcus faecalis.

[0014] Furthermore, the minimum inhibitory concentration (MIC) of the antimicrobial peptide AI18 is 8 μg / mL against Escherichia coli; 8 μg / mL against Pseudomonas aeruginosa; 8 μg / mL against Acinetobacter baumannii; 16 μg / mL against Klebsiella pneumoniae; 32 μg / mL against Staphylococcus aureus; 16 μg / mL against Propionibacterium acnes; and 32 μg / mL against Enterococcus faecalis.

[0015] The cells inhibited by the antimicrobial drug include both drug-resistant and non-drug-resistant bacteria. This invention demonstrates that the antimicrobial peptide AI18 exhibits good antimicrobial activity against both drug-resistant and non-drug-resistant Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae.

[0016] Compared to polymyxin E, the antimicrobial peptide AI18 provided by this invention has a longer duration of bactericidal activity against Escherichia coli, effectively preventing the development of bacterial resistance. Research in this invention shows that antimicrobial peptide AI18 possesses good in vivo antimicrobial activity and exerts a synergistic antimicrobial effect with components in plasma. Furthermore, it exhibits low hemolytic activity and demonstrates biocompatibility.

[0017] The antimicrobial peptide AI18 provided by this invention can also be applied to various scenarios where bacteria need to be killed or inhibited. Specifically, this invention also provides the application of antimicrobial peptide AI18 in the preparation of preservatives, daily chemical detergents, and medical devices with antimicrobial effects.

[0018] This invention provides a biological antimicrobial agent whose antimicrobial component includes the aforementioned antimicrobial peptide AI18. The antimicrobial peptide AI18 is combined with pharmaceutically or food-acceptable excipients to prepare the corresponding biological antimicrobial agent.

[0019] The present invention provides a preservative comprising the aforementioned antimicrobial peptide AI18.

[0020] Furthermore, the preservative is a preservative used in food or a preservative used in cosmetics.

[0021] The present invention provides a daily chemical detergent composition comprising the aforementioned antimicrobial peptide AI18.

[0022] Furthermore, the composition may be, but is not limited to, hand sanitizer, soap, shower gel, shampoo, toothpaste, laundry detergent, laundry powder, etc.

[0023] The present invention provides a medical dressing comprising the aforementioned antimicrobial peptide AI18 and a matrix.

[0024] The beneficial effects of this invention are as follows:

[0025] (1) The antimicrobial peptide AI18 provided by the present invention has broad-spectrum antimicrobial activity, especially for Gram-negative bacteria, drug-resistant bacteria and non-drug-resistant bacteria with significant antibacterial effect; animal model experiments show that antimicrobial peptide AI18 has good in vivo antimicrobial activity; antimicrobial peptide AI18 can exist relatively stably in plasma, and has extremely low hemolytic activity and good biosafety. It can be used for the treatment of bacterial infections, and can also be applied to other scenarios that require sterilization or inhibition of bacterial growth.

[0026] (2) The antimicrobial peptide AI18 provided by the present invention has a short sequence, small molecular weight, and low chemical synthesis difficulty, which can save the cost of large-scale production. Attached Figure Description

[0027] Figure 1 The time-kill curve of antimicrobial peptide AI18 against Escherichia coli ATCC 25922 is shown.

[0028] Figure 2 The hemolysis rate of antimicrobial peptide AI18 at different concentrations.

[0029] Figure 3 The study describes the induction of resistance to antimicrobial peptide AI18 in Escherichia coli ATCC 25922, where NOR represents norfloxacin and COL represents polymyxin E.

[0030] Figure 4 The results are from the plasma stability test of the antimicrobial peptide AI18.

[0031] Figure 5 This demonstrates the in vivo antibacterial activity of the antimicrobial peptide AI18.

[0032] Figure 6 Histological images of lung tissue sections. First row: Overview of lung tissue after H&E staining (scale bar, 500 μm). Second row: Detailed histological image of the black box region (scale bar, 100 μm). The experiment was repeated with similar results, showing a representative figure. The first column shows lung tissue images of mice in the PBS treatment group, the second column shows lung tissue images of mice in the AI18 treatment group, the third column shows lung tissue images of mice in the Indolicidin treatment group, and the fourth column shows lung tissue images of normal healthy mice. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the invention.

[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0035] The experimental materials used in the following examples:

[0036] 1. Strains

[0037] The standard strains used in this experiment were: Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 29213, Klebsiella pneumoniae ATCC 700603, Acinetobacter baumannii ATCC 19606, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Propionibacterium acnes ATCC 6919, and ATCC 11827.

[0038] Clinically resistant strains include: pan-drug resistant (PDR) Klebsiella pneumoniae 418015, extensive-drug resistant (XDR) Klebsiella pneumoniae 325016, multi-drug resistant (MDR) Klebsiella pneumoniae 327004, MDR Escherichia coli 103231, MDR Pseudomonas aeruginosa 304238, and MDR Acinetobacter baumannii 316039. Their drug susceptibility results are shown in Table 1.

[0039] Table 1. Antimicrobial susceptibility results of clinical strains

[0040]

[0041]

[0042] Note: R: drug resistance; S: sensitivity; I: intermediate.

[0043] 2. Pharmacology

[0044] Polymyxin E: CAS No. 1066-17-7, purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.; Norfloxacin: CAS No. 70458-96-7, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; Antimicrobial peptide Indolicidin: CAS No. 140896-21-5, purchased from Nanjing Peptide Valley Biotechnology Co., Ltd.

[0045] Example 1

[0046] 1. Preparation of antimicrobial peptide AI18

[0047] The antimicrobial peptide AI18 provided in this embodiment was designed using artificial intelligence technology. Its amino acid sequence is: AIPKRLRRFYLRALARRL (SEQ ID NO.1), with an amidation modification at the C-terminus. Specifically, its structure is Ala-Ile-Pro-Lys-Arg-Leu-Arg-Arg-Phe-Tyr-Leu-Arg-Ala-Leu-Ala-Arg-Arg-Leu-NH2. The antimicrobial peptide AI18 was synthesized by a biotechnology company using solid-phase synthesis.

[0048] 2. MIC determination of antimicrobial peptides

[0049] (1) MIC determination methods for Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli.

[0050] The MIC assay was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines, using the microbroth dilution method. First, the antimicrobial peptide was dissolved in sterile distilled water to an initial concentration of 5120 μg / mL and stored at 4°C. Before use, the antimicrobial peptide was diluted to 512 μg / mL with cationic-adjusted Mueller-Hinton broth (CAMHB), followed by a two-fold serial dilution in 96-well plates. The bacterial culture was adjusted to a 0.5 McFarland concentration, diluted 100-fold with fresh CAMHB, and 100 μL was added to each well of the 96-well plate containing the antimicrobial peptide to achieve a final bacterial concentration of 5 × 10⁻⁶. 5 CFU / mL. After incubation at 37°C for 18 hours, the MIC value is the minimum concentration of antimicrobial peptide at which no obvious bacterial growth is observed to the naked eye.

[0051] (2) MIC determination method for Propionibacterium acnes

[0052] Activated Propionibacterium acnes standard strains (including ATCC 6919 and ATCC 11827) were inoculated into BHI solid medium and incubated in an anaerobic bag at 37°C for 48 h. The bacterial concentration was then checked every hour under a microscope to determine the logarithmic growth phase. Once the bacterial cells reached the logarithmic growth phase, they were centrifuged at 7000 rpm for 10 min, and the precipitated cells were resuspended three times in fresh, sterile BHI medium. The OD values ​​were then measured. 600 Prepare a stock solution of approximately 0.3 μg / mL by dissolving the peptide in sterile distilled water. Design three replicates for each peptide / control drug. Add 200 μL of the drug solution to column 1, and 100 μL of the corresponding culture medium to columns 2-12. Starting from column 1, add 100 μL to the next column, repeatedly pipetting and diluting sequentially. Discard the last 100 μL of liquid in the last column, resulting in peptide concentrations of 128, 64, 32, 16, 8, 4, 2, 1, 0.5, 0.25, and 0.125 μg / mL. Set the concentration of the control drug, clindamycin, to the same level as the peptide. Adjust the bacterial culture concentration to 0.5 McFarland concentration and dilute 100-fold. Add 100 μL of the bacterial culture to the corresponding well. Place the 96-well plate in an anaerobic bag and incubate for 48 hours. The concentration observed in the clear wells is the minimum inhibitory concentration (MIC).

[0053] The results are shown in Tables 2 and 3.

[0054] Table 2. Antibacterial activity of AI18 against 8 standard strains

[0055] <![CDATA[MIC of antimicrobial peptide AI18 a (μg / mL)]]> <![CDATA[ATCC 29212 b ]]> 32 <![CDATA[ATCC 29213 c ]]> 32 <![CDATA[ATCC 700603 d ]]> 16 <![CDATA[ATCC 19606 e ]]> 8 <![CDATA[ATCC 27853 f ]]> 8 <![CDATA[ATCC 25922 g ]]> 8 <![CDATA[ATCC6919 h ]]> 16 <![CDATA[ATCC11827 h ]]> 16

[0056] Note: a: minimum inhibitory concentration; b: Enterococcus faecalis; c: Staphylococcus aureus; d: Klebsiella pneumoniae; e: Acinetobacter baumannii; f: Pseudomonas aeruginosa; g: Escherichia coli; h: Propionibacterium acnes; all quality controls were within acceptable limits, all growth control wells were turbid, and all blank control wells were clear.

[0057] Table 3. Antibacterial activity of AI18 against drug-resistant bacteria

[0058] MIC (μg / mL) of antimicrobial peptide AI18 418015 32 325016 8 327004 16 103231 4 304238 16 316039 8

[0059] As shown in Table 2, the MICs of AI18 against standard Klebsiella pneumoniae (ATCC 700603), Acinetobacter baumannii (ATCC 19606), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), and Propionibacterium acnes (ATCC 6919 and ATCC 11827) are all between 8 and 16 μg / mL.

[0060] As shown in Table 3, AI18 also exhibits good antibacterial activity against clinically resistant bacteria, with MICs ranging from 4 to 32 μg / mL.

[0061] 3. Time-based sterilization experiment

[0062] The bactericidal kinetics of AI18 against standard Escherichia coli ATCC 25922 were investigated. E. coli culture 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 3-4 hours to induce the logarithmic growth phase. Three shake tubes were prepared by adding 10 mL of 4×MIC polymyxin E, AI18 at concentrations of 2 μg / mL and 32 μg / mL, respectively, to CAMHB medium. Another shake tube was prepared by adding 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 four shake tubes to achieve a final bacterial concentration of 3×10⁻⁶. 6 CFU / mL was incubated at 37°C and 150 rpm. At 0, 2, 4, 6, 18, and 24 hours, the medium was serially diluted 10-fold with fresh CAMHB medium and dropped onto Mueller-Hinton agar (MHA) plates, incubated at 37°C and 150 rpm for 18–24 hours, and the results were read. No antimicrobial peptide was used as a blank control, and polymyxin E was used as a positive control.

[0063] The results are as follows Figure 1As shown, 4×MIC AI18 killed all E. coli within 2 hours, and no E. coli could revive until 24 hours. While 4×MIC polymyxin E exerted a rapid bactericidal effect within 2 hours, bacteria gradually resumed growth after 6 hours of co-incubation, and the bacterial concentration at 18 hours was comparable to the blank control group. This indicates that AI18's bactericidal rate against standard E. coli is comparable to that of polymyxin E, but its duration of action is longer.

[0064] 4. Antimicrobial peptide hemolysis test

[0065] Fresh human red blood cells (RBCs) were washed three times with sterile PBS and then added to 96-well U-shaped plates containing different concentrations of antimicrobial peptides, resulting in an RBC concentration of 2% and an antimicrobial peptide concentration of 1000–7.8 μg / mL, with a final volume of 200 μL per well. RBCs treated with PBS alone served as a negative control, and RBCs treated with 0.5% Triton X-100 served as a positive control. After incubation at 37°C for 1 hour, the plates were centrifuged at 1200g for 15 minutes at 4°C. The supernatant was collected in new flat-bottomed 96-well plates, and the OD was measured. 570 The hemolysis rate is calculated using the following formula:

[0066]

[0067] The results are as follows Figure 2 As shown, the half-maximal hemolytic value (HC) of AI18 50 A concentration greater than 1000 μg / mL indicates very low hemolytic activity.

[0068] 5. Antimicrobial peptides induce drug resistance

[0069] Antimicrobial peptides exert their antibacterial effects primarily by affecting cell membrane permeability. Their mechanisms of action are not limited to specific targets, making it difficult for bacteria to develop resistance. This study investigated the induction of drug resistance in *Escherichia coli* ATCC 25922 by the antimicrobial peptide AI18.

[0070] E. coli ATCC 25922 in logarithmic growth phase was adjusted to a McFarland concentration of 0.5% using CAMHB medium. This was then diluted 100-fold with fresh CAMHB medium and added to 96-well plates containing gradient concentrations of antimicrobial peptides. The plates were incubated at 37°C for 18 hours, and the MIC was read. After 24 hours of incubation, the bacterial culture that could grow at the maximum drug concentration was diluted 1:10000 with fresh CAMHB medium and added to 96-well plates containing gradient concentrations of antimicrobial peptides. The second-generation MIC was read after 18 hours of incubation. The same method was used to passage the next generation at 24 hours, for a total of 30 passages.

[0071] The induction of drug resistance in Escherichia coli ATCC 25922 by norfloxacin and polymyxin E was also compared.

[0072] The results are as follows Figure 3 As shown, after 30 consecutive passages of the antimicrobial peptide AI18 at 1 / 2×MIC, no drug resistance was developed in *E. coli*. In contrast, the MIC value of the control antibiotic norfloxacin increased 16-fold after 17 consecutive passages, and further increased to 128-fold after 30 consecutive passages, indicating significant resistance in *E. coli* to norfloxacin. Therefore, the antimicrobial peptide AI18 can effectively prevent the development of bacterial resistance.

[0073] 6. Plasma stability test

[0074] Sterile human blood was centrifuged at 3500 rpm for 10 minutes to obtain the supernatant, i.e., fresh plasma. AI18 was dissolved in water and fresh plasma at a volume ratio of 1:1 to prepare a stock solution of 2500 μg / mL.

[0075] The test tube was gently shaken at 100 rpm in a shaker at 37°C. 200 μL of sample was collected at 0, 60, 120, and 240 minutes, and 800 μL of a mixed solvent containing 1% acetic acid (10% methanol, 10% water, 80% acetonitrile) was added to prevent further degradation of AI18. After centrifugation, the supernatant was collected and analyzed by high-performance liquid chromatography (HPLC) using an Agilent ZORBAX C18 reversed-phase column (5 μm, 4.6 × 250 mm). The mobile phase was A phase: acetonitrile (containing 0.1% trifluoroacetic acid); B phase: deionized water (containing 0.1% trifluoroacetic acid). Gradient elution was performed from 10% to 99% of phase A for 33 minutes at a flow rate of 1 mL / min. The absorbance was measured at 214 nm. The experiment was repeated three times.

[0076] The plasma stability test results of antimicrobial peptide AI18 are as follows: Figure 4 As shown, less than 40% of AI18 was degraded in human plasma within 4 hours, indicating that AI18 can exist relatively stably in human blood.

[0077] 7. Mouse pneumonia infection model

[0078] To further evaluate the in vivo activity of the antimicrobial peptide AI18, it was used to treat mice with neutropenia and pneumonia caused by XDR Klebsiella pneumoniae (325016).

[0079] Eighteen healthy male BALB / c mice (6-8 weeks old, 20±2g) were used to obtain a neutropenic mouse model by intraperitoneal injection of cyclophosphamide at 150 mg / kg and 100 mg / kg, respectively, 4 days and 1 day before modeling. On the day of modeling, mice were anesthetized with isoflurane, and then 40 μL of logarithmic-phase XDR Klebsiella pneumoniae 325016 (washed three times with PBS and adjusted to 1×10⁻⁶) was infused intratracheally. 6Modeling was performed using CFU / mL.

[0080] The mice were then randomly divided into three groups of six each. Two hours and twelve hours post-infection, the mice were intraperitoneally injected with 10 mg / kg of AI18, Indolicidin, or an equivalent volume of PBS.

[0081] All mice were euthanized 24 hours after modeling. Lung tissue was harvested under aseptic conditions, weighed, and homogenized with 1 mL of sterile PBS. The lung tissue homogenate was serially diluted 10-fold with sterile PBS and dropped onto MH agar plates. After incubation at 37°C for 18-24 hours, colony counts were performed and the bacterial load of the lung tissue was calculated.

[0082] The results are as follows Figure 5 As shown, the bacterial load in the lung tissue of mice in the AI18 group was significantly lower than that in the blank control group (PBS group), and its therapeutic effect was comparable to that of the positive control group's antimicrobial peptide, Indolicidin. This indicates that AI18 has good in vivo antimicrobial activity.

[0083] Lung tissues from the three treatment groups and lung tissues from healthy male BALB / c mice (6-8 weeks old, 20±2g) were fixed in 4% paraformaldehyde for 24 hours, rinsed with running water for about 2 hours, dehydrated with graded ethanol, cleared with xylene, and embedded in paraffin. After the paraffin blocks cooled, they were trimmed with a blade and sectioned into 5μm thick sections using a rotary microtome. The tissues were flattened in 40℃ warm water, placed on anti-detachment glass slides, and heated on a slide warmer until all moisture was removed, allowing the tissues to adhere to the slides. The tissues were dewaxed and rehydrated, stained in hematoxylin for 5 min, rinsed with running water for 5 min, differentiated in 1% hydrochloric acid ethanol for about 30 s, and rinsed with running water for 5 min. They were then infused with 1% weak ammonia solution to achieve a blue inversion for 1 min, and rinsed with running water for 5 min. Finally, they were ethanolified in 80% ethanol for 2 min and stained in eosin for 2 min. After dehydration, clearing, and mounting, the slides were prepared.

[0084] The results are as follows Figure 6 As shown, compared to the PBS treatment group, the AI18 group had a significant reduction in inflammatory cells, and was also slightly better than the positive control group (indolicidin). Compared to normal mouse lung tissue (Normal group), the lung tissue after AI18 administration was no different, indicating that AI18 has good biocompatibility.

Claims

1. An antimicrobial peptide AI18, characterized in that, Its amino acid sequence is shown in SEQ ID NO.1, and its C-terminus is amidated.

2. The use of the antimicrobial peptide AI18 as described in claim 1 in the preparation of a medicament for inhibiting Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, Propionibacterium acnes, or Enterococcus faecalis.

3. The application of the antimicrobial peptide AI18 as described in claim 1 in the preparation of preservatives, daily chemical detergents, and medical devices with antimicrobial effects.

4. A biological antibacterial agent, characterized in that, Its antibacterial component is the antimicrobial peptide AI18 as described in claim 1.

5. A preservative, characterized in that, Includes the antimicrobial peptide AI18 as described in claim 1.

6. The preservative as described in claim 5, characterized in that, The preservative is a preservative used in food or a preservative used in cosmetics.

7. A daily chemical detergent composition, characterized in that, Includes the antimicrobial peptide AI18 as described in claim 1.

8. A medical dressing, characterized in that, Includes the antimicrobial peptide AI18 as described in claim 1.

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