Studies on antagonistic effect between Lactobacillus sakei, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus

The antimicrobial activity of a commercial probiotic culture, Lactobacillus sakei (ATCC 1521) at following concentrations (30, 42, 60, 78 and 90 μg/ml, 105 - 107UFC/mL), temperatures of interaction (4, 10, 20, 30, 37 °C) and initial pH (3.5, 4.0, 4.5, 5.0 and 5.5) were tested against three foodborne pathogens, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus. The antagonistic effect of the probiotic culture in vitro was performed by liquid microdilution method. The results indicated that the inhibitory substance present on a 24 hours culture broth could be an advantage when keeping the culture dominant during longer fermentations. For the highest lactic acid production, the incubation period of lactic acid bacteria (1.04 % v/v) was on MRS Broth in aerobic conditions, at 37 oC/24 hours, which gave a minimum pH value of the supernatant (3.5). The data suggest that supernatant can have significant bacteriostatic activity against E. coli, L. monocytogenes and S. aureus, and may provide cured meats with a degree of protection against this microorganism, particularly if employed with a combination of acid pH, and adequate refrigeration.