Antimicrobial activity of cell-free supernatant and extracellular vesicles from Ligilactobacillus salivarius PM-A0006 against Staphylococcus aureus

Ligilactobacillus salivarius has been identified as a putative probiotic, its functional mechanisms and genomic characteristics remain under investigated. In this study, L. salivarius strain PM-A0006 was comprehensively evaluated through integrated whole-genome sequencing and phenotypic characterization. Whole-genome sequencing of L. salivarius PM-A0006 revealed a circular chromosome of 1,877,957 bp with GC content of 32.96% and no virulence factor-related genes were identified. The antibacterial and anti-biofilm activity of cell-free supernatant (CFS) and extracellular vesicles (EVs) was tested on Staphylococcus aureus (ATCC25923) using measurement of inhibition-zone diameters, minimum inhibitory concentration, crystal violet staining and scanning electron microscopy. The results demonstrated that both the CFS and EVs exhibited robust antibacterial and anti-biofilm activities. Liquid chromatography-mass spectrometry analysis revealed that the CFS and EVs were rich in phenyllactic acid, which may be related to their antibacterial properties. Probiotic-derived CFS and EVs are promising antimicrobial candidates due to their safety profiles and multifaceted health benefits. This study demonstrates that the metabolites of L. salivarius PM-A0006 present a safe and potential alternative strategy for preventing staphylococcal risk in food safety.