The species-specific mode of action of the antimicrobial peptide subtilosin against Listeria monocytogenes Scott A

Aims: To elucidate the molecular mechanism of action of the antimicrobial peptide subtilosin against the foodborne pathogen Listeria monocytogenes Scott A. Methods and Results: Subtilosin was purified from a culture of Bacillus amylliquefaciens. The minimal inhibitory concentration of subtilosin against L. moilocytogenes Scott A was determined by broth microdilution method. The effect of subtilosin on the transmembrane electrical potential (Ali) and pH gradient (ApH), and its ability to induce efflux of intracellular ATP, was investigated. Subtilosin fully inhibited L. monocytogencs growth at a concentration of 19 fig Subtilosin caused a partial depletion of the AT and had a similar minor effect on the ApIL There was no significant efflux of intracellular ATP. Conclusion: Subtilosin likely acts upon L. monocytogencs Scott A by perturbing the lipid bilayer of the cellular membrane and causing intracellular damage, leading to eventual cell death. Subtilosin's mode of action against L. monocytogcues Scott A differs from the one previously described for another human path()gen, Cam dnerella vaginalis. Significance and Impact of the Study: This is the first report on the specific mode of action of subtilosin against L. monocytogenes and the first report of a bacteriocin with a species specific mode of action.