Abstract
BackgroundAs 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.ResultsThis 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.ConclusionThese results showed that the antimicrobial mechanism of ε-PL against S. aureus was a synergistic action.
Highlights
As a natural antibacterial cationic peptide, ε-poly-l-lysine (ε-PL) is applied as a food preservative
Some reports indicated that the minimal inhibitory concentrations (MIC) value of ε-PL against S. aureus was below 20 mg/mL (Li et al 2014; Zhou et al 2011)
The results indicated that antimicrobial activity of ε-PL against S. aureus had primarily dependence on concentrations of ε-PL
Summary
As a natural antibacterial cationic peptide, ε-poly-l-lysine (ε-PL) is applied as a food preservative. Its antimicrobial mechanism at the metabolomics has not been yet thoroughly described. As a natural antimicrobial peptide, ε-PL can inhibit various microorganisms, such as most of bacteria, yeast, and virus (Shukla et al 2012). The destructive effect of ε-PL on cell structure was further demonstrated by the same group (Lin et al 2018). Researchers agree that the antimicrobial effect of ε-PL is to destroy cell membranes or cell walls (Zhang et al 2018; Li et al 2014; Melo et al 2009). Little information is available about the effect of ε-PL at different concentration on antimicrobial activity and the mechanisms involved
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