Antimicrobial ε-poly-l-lysine induced changes in cell membrane compositions and properties of Saccharomyces cerevisiae

ε-Poly-l-lysine (ε-PL) is a natural antimicrobial poly-cationic peptide, and it has been widely used as a food preservative. However, the detailed antimicrobial mechanism of ε-PL remains unclear. Currently, it is widely accepted that membrane disruption is its main antimicrobial mode of action, but its effect on the cell membrane composition and fluidity remains unclear. In this study, we investigated the effect of ε-PL on ergosterol and fatty acids as well as fluidity of the cell membrane of Saccharomyces cerevisiae. Compared with the control, the level of ergosterol increased significantly by ε-PL. ε-PL also caused changes in the membrane fatty acid composition. A slight increase in the fluidity of cell membrane and plasmolysed cells as well as some membrane curvature changes were observed under a transmission electron microscope. ε-PL also induced osmotic stress by breaking ionic balance between inside and outside of the membrane.