?-Poly-l-lysine and nisin A act synergistically against Gram-positive food-borne pathogens Bacillus cereus and Listeria monocytogenes

AIMS: To test epsilon-poly-L-lysine and nisin A for possible synergistic activity against selected food-borne pathogens and food spoilage organisms. METHODS AND RESULTS: Synergistic activity was observed against Gram-positive Listeria monocytogenes and Bacillus cereus cells and spores of B. cereus in 96 well plate assays. However, nisin A had no effect alone or in combination with epsilon-poly-L-lysine against Gram-negative Escherichia coli cells. In addition, when tested against yeast Zygosaccharomyces bailii, nisin A and partially inhibitory concentrations of epsilon-poly-L-lysine antagonized each other. CONCLUSIONS: Nisin A and epsilon-poly-L-lysine showed synergistic activity against B. cereus and L. monocytogenes. SIGNIFICANCE AND IMPACT OF THE STUDY: The application of nisin A and epsilon-poly-L-lysine is a promising all-natural method of controlling Gram-positive food-borne pathogens, spores and spoilage organisms.