Discovery, characterization, and application of a novel antimicrobial peptide produced by Lactiplantibacillus plantarum FB-2

Bacteriocins produced by lactic acid bacteria (LAB) are of interest due to their promising applications in the food industry. In this study, Plantaricin FB-2 was separated to two fractions (FB-2A, FB-2B) by gel filtration chromatography and FB-2A was chosen with higher antibacterial activity. FB-2A was further characterized by reversed-phase high performance liquid chromatography (RP-HPLC) coupled, purified AMP KMY15 was obtained and possessed antibacterial activity against Staphylococcus aureus ATCC6538 (MIC = 256 μg/mL), Escherichia coli DH5α (MIC = 128 μg/mL), Salmonella Typhimurium CICI10437 (MIC = 512 μg/mL), and Listeria monocytogenes ATCC19115 (MIC = 256 μg/mL). The amino acid sequence of KMY15 was identified as KMYKKGRLWLVAGLS. It hemolytic activities were lower than 5 %, and it co-cultures well with RAW 264.7 macrophage cells. Further Scanning Electron Microscope (SEM) also showed that KMY15 can distinctively act on the bacterial membrane leading to the leakage of cellular contents. The quantification of apoptosis using a flow cytometry (FCM) analysis further confirmed that the mortality rates of S. aureus ATCC6538 and E. coli DH5α were 63.0 % and 87.0 %, respectively, after 8 h of treatment with KMY15. It effectively mitigates the growth of S. aureus ATCC6538 in milk. Complete genome sequencing of Lactiplantibacillus plantarum FB-2 reveals the relationship between KMY15 and the genome. In conclusion, KMY15 is a potent preservative and antibacterial agent.