The Investigation of Probiotic Potential of Lactic Acid Bacteria Isolated from Traditional Dairy Products and Their Genomic Analysis in Northern Iran

Isolation, identification and selection of the best Lactobacillus with probiotic activity from local dairy products of Gilan province. In this study, 30 isolates obtained from local dairy products in rural areas of Gilan were identified microbiologically and biochemically. The probiotic characteristics of the strains were determined and antagonistic activity of the extract of Lactobacillus isolates against five pathogenic bacteria by the well method in agar, and antibiogram by the disk diffusion method and finally the isolates were identified based on the 16SrRNA sequence. Among the isolates, four strains with the best results in terms of probiotic performance were identified. In the investigation of antimicrobial activity, the isolates were able to inhibit the growth of Staphylococcus aureus, Shigella flexneri, Pseudomonas aeruginosa and Uropathogenic Escherichia coli, but they had no significant inhibitory effect on the growth of Bacillus cereus. Antibiogram results showed that all four strains were resistant to vancomycin and gentamicin but sensitive to ampicillin. None of the isolates showed hemolytic activity. Only two strains showed a clear band in the genomic analysis of 16srRNA by PCR method. The affinity of the strains indicated Lactobacillus delbrueckii subspecies bulgaricus. The extract of these two strains without neutralization and catalase enzyme showed the best activity against common pathogenic bacteria. According to the available results, our strain can be used as a suitable candidate as a supplement in the prevention and biological treatment of some clinical cases in laboratory and in vivo conditions with further research.