Antimicrobial potential of Leuconostoc species against E. coli O157:H7 in ground meat

Ground beef is risky by foodborne pathogens such as E. coli O157:H7 due to the cross-contamination during grinding. The objective of this study was to evaluate the antagonistic activities of Leuconostoc species isolated from ground beef product in order to limit the growth of E. coli O157:H7. While Leuconostoc has been known as spoilage bacteria, the Leuconostoc isolates showed antimicrobial activity on foodborne pathogens such as E. coli O157:H7, Salmonella, Staphylococcus aureus, Listeria monocytogenes, and meat-spoilage bacteria Brochothrix thermosphacta. Antimicrobial activity of cell-free supernatant (CFS) was evaluated by heat, enzyme, and pH adjustment and antagonistic activity by cell competitive growth. In addition, CFS concentration was screened for the presence of organic acids for the antimicrobial properties. Regulation of virulence genes was investigated by inhibition of locus of enterocyte effacement expression by CFS. The result showed that Leuconostoc isolates inhibited the growth of E. coli O157:H7 by active antimicrobial agent including organic acids and the growth of background microorganisms, and E. coli O157:H7 in ground beef was inhibited with the supplement of the CFS.