Antibacterial mechanism of the novel lipopeptide M3 against Listeria monocytogenes and its application in fish preservation

A novel lipopeptide was developed in this study by modifying C16 fengycin A through amino acid substitutions, producing M1–M5. Notably, M3 exhibited a minimum inhibitory concentration of 4 μg/mL against Listeria monocytogenes, which was significantly lower than that of the parent peptide and other derivative peptides. Mechanism studies revealed that M3 disrupted the integrity and permeability of bacterial cell membranes, induced membrane depolarization, and interfered with key pathways, such as fatty acid metabolism and glycerophospholipid metabolism, thereby inhibiting membrane lipid synthesis. A metabolomics analysis indicated that M3 treatment altered bacterial metabolites primarily enriched in pathways related to unsaturated fatty acid biosynthesis and glycerophospholipid metabolism, with abnormal activity of key enzymes such as NADPH oxidase and biotin carboxylase. Additionally, M3 demonstrated excellent performance in fish preservation experiments: after 14 days of storage at 4 °C, the total volatile basic nitrogen in fish meat treated with M3 was below the spoilage threshold, an increase in the total bacterial count was significantly delayed, and quality indicators such as color, texture, and water retention were well maintained. This study provides a theoretical basis for the application of M3 as a natural antibacterial agent in the food industry.