Antagonistic effect of native lactic acid bacteria against foodborne bacterial pathogens

Identification of lactic acid bacteria, bacteriocin producing has been noticeable by most researchers. The surveys showed that bacteriocins of lactic acid bacteria has antibacterial effect against bacteria of poisoning agent, so these bacteriocins could be used as natural preserving of food materials. In this research, antimicrobial activities of bacterial supernatant from 10 native strain of lactic acid bacteria existing in Biotechnology Research Institute of Iran (ABRII), Branch of North-West and West Region of Iran evaluated by disk diffusion assay against seven pathogen including Listeria innocua, Bacillus cereus, flexneri Shigella, Escherichia coli, Staphylococcus aureus, Yersinia entrocolitica, Klebsiella pneumonia. Each test had three replications and the inhibition zone diameter measured in strains and compared with each other. At next step, peptide identification of antibacterial agent was detected by trypsin enzyme treatment. The results represented that lactic acid strains represented good antimicrobial potential against seven bacteria of poisoning agent. Also 15E strain with 6.03mm and 0.167mm inhibition zone diameter versus flexneri shigella and Yersinia entrocolitica showed the highest and lowest rate of suppression, respectively. Escherichia coli and Shigella flexneri the sensitive and Bacillus cereus as resistant strain was detected against bacteriocins of lactic acid bacteria. Also enzyme treatment result confirm peptide identification of antibacterial agent. T2 native strain could consider as strain with high potential versus gram-negative bacteria like Flexneri shigella, E. coli, Yersinia entrocolitica, and Klebsiella pneumonia.