Antimicrobial activity of Arg–Ser–Ser against the food‐borne pathogen Pseudomonas aeruginosa

We had previously reported a peptide sequence, Arg–Ser–Ser (RSS), which was identified after coincubation of an edible orchid species, Dendrobium aphyllum, with Lactobacillus amylolyticus. In this study, we investigated the potential mechanism of the antibacterial effect of RSS on the pathogen Pseudomonas aeruginosa. The minimum inhibitory concentration of RSS for P. aeruginosa was 6.3%, and the peptide was shown to induce morphological damage to bacterial cells. RSS treatment increased the cell surface zeta potential, hydrophobicity and cell membrane permeability, indicating that the positively charged RSS likely interacted with the negatively charged bacterial membrane. Moreover, leakage of potassium ions and proteins from bacterial cells was increased by RSS by 30 ppm and 13.5 μg mL⁻¹, respectively. In conclusion, RSS treatment caused leakage of cellular components from P. aeruginosa cells, mainly through damaging the cell membrane by electrostatic action. Thus, RSS may be a potent new antimicrobial agent.