Antibacterial Activity of Lactiplantibacillus Strains Isolated from Commercial Yogurt against Foodborne Pathogenic Bacteria

Background and Objective: Lactic acid bacteria are well known as beneficial microorganisms and most of them are probiotic distributed widely, especially in fermented dairy products e.g. yogurt. This study aimed to isolate, characterize and assess antibacterial effects of lactic acid bacteria that produce bacteriocin-like inhibitory substances against foodborne pathogenic bacteria. Material and Methods: In the present study, 17 lactic acid bacteria strains were isolated from 10 commercial yogurt samples and the antibacterial effects of lactic acid bacterial cell culture, cell- free supernatant and neutralized cell-free supernatant were assessed against standard foodborne pathogenic bacteria of Escherichia coli , , Listeria monocytogenes, Klebsiella pneumonia and Salmonella typhimurium using agar well diffusion assay. . Although various treatments were used, most of the lactic acid bacterial isolates showed antibacterial activity against the foodborne pathogenic bacteria. Moreover, Lactiplantibacillus pentosus (SY1), Lacticaseibacillus rhamnosus (SY5), Lactiplantibacillus plantarum (SY8) and Lactiplantibacillus plantarum (SY9) showed significantly the best antibacterial activity against the foodborne pathogens and thus were further identified using 16S rRNA gene molecular method. Results and Conclusion: Results showed that four isolates could produce bacteriocin-like inhibitory substances, which were significantly effective to inhibit growth of the pathogens. Primary screening for antibacterial activity showed that 10 lactic acid bacterial strains inhibited Escherichia coli. . The results revealed that Listeria monocytogenes was inhibited by six lactic acid bacterial isolates, while Salmonella typhimurium was inhibited by one lactic acid bacterial isolate. Moreover, results showed that Klebsiella pneumoniae was not affected by the isolates or treatment methods. It is concluded that the bacteriocin-like inhibitory substance of lactic acid bacterial isolates was effective; hence, it could be used as a natural food additive to prevent foodborne infections and improve the food quality. Conflict of interest: : The authors declare no conflict of interest.