The increasing emergence of multidrug-resistant pathogens
and development
of biopreservatives in food industries has increased the demand of
novel and safe antimicrobial agents. In this study, a marine bacterial
strain Bacillus licheniformis M1 was
isolated and exhibited obvious antimicrobial activities against foodborne
pathogens, especially against methicillin-resistant Staphylococcus aureus. The antimicrobial agent was
purified and identified as a novel antimicrobial peptide, which was
designated as bacipeptin, and the corresponding mechanism was further
investigated by electron microscopy observation and transcriptomic
analysis with biochemical validation. The results showed that bacipeptin
could reduce the virulence of methicillin-resistant Staphylococcus aureus and exerted its antimicrobial
activity by interfering with histidine metabolism, inducing the accumulation
of reactive oxygen species and down-regulating genes related to Na+/H+ antiporter and the cell wall, thus causing
damage to the cell wall and membrane. Overall, our study provides
a novel natural product against foodborne pathogens and discloses
the corresponding action mechanism.