Bacteriocin-Mediated Antagonistic Activity of Lactococcus lactis S93 against Foodborne Pathogens

Lactic acid bacteria (LAB) have long been recognized for their significant role in food preservation, fermentation and human health. They exhibit antimicrobial properties through the production of organic acids, hydrogen peroxide and bacteriocins which can effectively inhibit the growth of spoilage organisms and pathogenic bacteria. Among LAB, Lactococcus lactis is widely studied for its potential as a natural biopreservative due to its ability to produce antimicrobial peptides known as bacteriocins. This study aims to investigate the antagonistic effect of Lactococcus lactis subsp. lactis S93 against several foodborne pathogens, including Escherichia coli, Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes and Enterococcus faecalis. By utilizing the agar overlay technique, inhibition zones were measured to determine the extent of bacterial suppression. The inhibitory compounds were further characterized by evaluating the effects of neutralized pH and enzymatic treatments. The results demonstrated that Lactococcus lactis S93 effectively inhibited the growth of all tested pathogens, primarily through the production of bacteriocins and organic acids. Furthermore, the observed effect was determined to be bacteriostatic rather than bactericidal, suggesting its potential application as a biopreservative in food products. These findings contribute to the growing body of research supporting the use of Lactococcus lactis strains for improving food safety and shelf-life. Future research should focus on optimizing bacteriocin production and assessing its efficacy in real food matrices.