Synergistic antibacterial action of heat in combination with nisin and magainin II amide

Lactobacillus plantarum has been exposed to mild heat at temperatures between 48 and 56 degrees C in combination with low concentrations of the lantobiotic nisin in different sequential set-ups. Exposure to heat and nisin caused synergistic reductions of Lact. plantarum viability. Efficient antimicrobial action was dependent on the growth state of the culture as well as on levels and sequences of treatment applications. Listeria monocytogenes and Escherichia coli were treated at 55 degrees C in the presence of magainin II amide. Synergistic reductions in viable counts could be observed for L. monocytogenes and, after prolonged exposure, also for E. cell. The bacterial membrane could be identified by fluorometry and flow cytometry as an important target of applied treatment combinations.