该研究以L. paracasei subsp. Tolerans FX-6为出发菌株，经过60Co γ射线辐照诱变，筛选出一株高产抗菌肽F1的突变菌株（菌26）。对菌26进行16S rDNA序列比较分析发现其与FX-6具有高度相似性。进一步对菌26的牛奶发酵粗提物进行分离纯化，成功富集抗菌肽F1。通过抑菌实验发现，菌26的牛奶发酵粗提物对E. coli的最低抑菌质量浓度（Minimum Inhibitory Concentration, MIC）为3.16 mg/mL，较FX-6牛奶发酵粗提物的MIC降低了75%，同时抗菌肽F1的产量也提高了3.03倍，初步推断抗菌肽F1质量浓度与菌株的抑菌活性之间可能存在正相关关系。前期研究已经发现抗菌肽F1对黏菌素耐药大肠杆菌SHP45的MIC为320.0 μg/mL，该实验进一步研究表明当抗菌肽F1的质量浓度达到2×MIC时，可抑制50%以上的黏菌素耐药大肠杆菌SHP45生物膜的形成。基于以上研究结果表明，菌26比出发菌株具有更高的产抗菌肽F1能力，且抗菌肽F1对黏菌素耐药大肠杆菌SHP45的生物膜形成具有显著的抑制作用。该研究为高产抗菌肽菌株的获得提供研究思路，并有望为多重耐药细菌感染的防控提供物质基础。

Lactobacillus paracasei subsp. tolerans FX-6, as the original starting strain, was mutated through 60Co γ-ray irradiation. A strain (Strain 26) producing antimicrobial peptide F1 at high yield was identified from the mutated strains. High similarity between FX-6 and strain 26 was revealed through comparative analysis of their 16S rDNA sequences. The crude extract of milk fermented by Strain 26 was further purified to successfully enrich antimicrobial peptide F1. Bacteriostatic experiments showed that the minimum inhibitory concentration (MIC) of the crude extract of milk fermented by Strain 26 on Escherichia coli was 3.16 mg/mL, which was 75% lower than the MIC of the crudee xtract of milk fermented by FX-6, and the yield of antimicrobial peptide F1 by Strain 26 was 3.03-fold that by FX-6. The results preliminarily indicate a possible positive correlation between the concentration of antimicrobial peptide F1 and the antimicrobial activity of the strain. Our preliminary results have shown that the MIC of antimicrobial peptide F1 against colistin-resistant E. coli SHP45 was 320.0 μg/mL, and the results of this study further demonstrated that the biofilm formation in colistin-resistant E. coli SHP45 was inhibited by over 50% when the concentration of antimicrobial peptide F1 reached 2× MIC. These findings indicate that Strain 26 exhibited a stronger ability to produce antimicrobial peptide F1 than FX-6 and that antimicrobial peptide F1 significantly inhibited biofilm formation in colistin-resistant E. coli SHP45. This study offers insights into obtaining strains producing antimicrobial peptide F1 at high yield and is expected to serve as a material basis for the prevention and control of multidrug-resistant bacterial infections.

国家自然科学基金项目（31972018）