The antimicrobial effects and mechanism of ε-poly-lysine against Staphylococcus aureus

Background As a natural antibacterial cationic peptide, ε-poly-l-lysine (ε-PL) is applied as a food preservative. However, the mechanism of ε-PL against Staphylococcus aureus (S. aureus) has not been elucidated. Especially, its antimicrobial mechanism at the metabolomics has not been yet thoroughly described. Results This work aimed at clarifying the antibacterial activity and mechanism of ε-PL against S. aureus. Effects of ε-PL with different concentration on cell morphology, cell wall, and membrane integrity were investigated. Furthermore, the effect of ε-PL on metabolite properties of S. aureus was also studied. The results revealed that ε-PL disrupted the cell wall and membrane integrity of treated cells. ε-PL induced the structural change of peptidoglycan in cell wall, causing cell wall more fragile. Meanwhile, the permeability of the S. aureus cell membrane was increased by ε-PL. More importantly, ε-PL with different concentration could cause different effects on metabolic pathways of S. aureus. ε-PL with high concentration could directly restrain the central carbon metabolism. However, ε-PL with low concentration could only inhibit the glycolytic pathway. Conclusion These results showed that the antimicrobial mechanism of ε-PL against S. aureus was a synergistic action.