Activity of dermaseptin K4-S4 against foodborne pathogens

Dermaseptin S4 and its substituted derivative K(4)-S4 were investigated against various food-related pathogenic bacteria in culture media. K(4)-S4, but not the native peptide displayed significant growth inhibitory activity against all bacteria tested. Next, activity of K(4)-S4 against Escherichia coli O157:H7 was defined in terms of milieu dependencies. Salt-dependent kinetic studies in growth medium indicated that the peptide's antibacterial activity is maintained at fairly high (up to 600mM) NaCl concentrations but inhibited at higher concentrations. Similarly, antibacterial activity was reduced at high but not low pH conditions. Importantly, antibacterial activity was significantly maintained at temperatures lower than 37 degrees C and significantly enhanced at 42 degrees C. With respect to bactericidal kinetics, negative cultures were obtained in LB as well as in commercial apple juice, respectively, within 1 and 2h treatment, at twice the minimal inhibitory concentration (MIC) value. Overall, the data collected is indicative of a certain interest for dermaseptin derivatives as potential food preservatives.