Antibacterial characteristics and mechanisms of -poly-lysine against Escherichia coli and Staphylococcus aureus

The aim of this study was to investigate the antibacterial characteristics and antibacterial mechanisms of 3-poly-lysine against Escherichia coli and Staphylococcus aureus. The diameters of inhibition zones of E. coli (10 0.5 mm) and S. aureus (12 0.1 mm) treated by 200 mg/ml 3-poly-lysine were much larger than control (5 0.3 mm) (p < 0.05). Minimum inhibition concentration of 3-poly-lysine against E. coli and S. aureus was 12.5 mg/ml. Scanning electron microscopy showed that 3-poly-lysine damaged the morphology of tested bacterial cells. The increase in electric conductivity of bacterial cells suspension indicated that the cytoplasmic membranes were broken by 3-poly-lysine, which caused leakage of ions in cells. SDS-PAGE of bacterial proteins demonstrated that 3-poly-lysine could damage bacterial cells through the destruction of cellular proteins. These results indicated that 3-poly-lysine has good potential to be as a natural food preservative. 2014 Elsevier Ltd. All rights reserved.