Viability Loss of Foodborne Pathogens by Starter Culture Metabolites

Antibacterial metabolites produced by starter culture bacteria were tested for inhibitory properties against foodborne pathogens capable of growing in foods at refrigeration temperature. Three culture preparations containing the bacteriocins pediocin AcH, nisin, and sakacin A produced by Pediococcus acidilactici H, Lactococcus lactis ssp. lactis DL 16, and Lactobacillus sake 706, respectively, were studied in addition to four commercial preparations: Nisaplin (similar to nisin), Na-lactate, diacetyl and Microgard. All bacteriocin preparations were bactericidal to the Listeria strains tested including nine strains of L. monocytogenes , but not to any of the gram-negative pathogens studied. Some strains of Listeria were lysed by pediocin AcH. Storage studies at 4°C indicated that the bacteriocin preparations did not have bacteriostatic properties against the surviving cells. Diacetyl produced some bactericidal effect against strains of Yersinia enterocolitica , Aeromonas hydrophila , pathogenic Escherichia coli , and Salmonella anatum , but not against Listeria . Lactate had limited bacteriostatic effect against gram-negative pathogens and none against the gram-positive bacteria. Microgard had neither bactericidal nor bacteriostatic action against the bacteria used in this study.