Abstract

Background/objective: Probiotics are living microorganisms that have beneficial health effects when consumed in sufficient quantities. Among bacteria, Lactobacillus are the most common type of bacteria that have been identified as probiotics.

Materials and Methods: This study isolated Lactobacillus from the traditional yogurt, dooghd and, curd of Mazandaran Province in Iran and investigated their probiotic potency and antimicrobial effect on Escherichia coli. For this purpose, Lactobacillus were isolated by phenotypic , morphology and biochemical tests of acid resistance and bile salt tolerance tests, and their primary probiotic index was evaluated. The inhibitory effect of the isolated bacteria on E. coli was investigated by the disk-diffusion agar method. The non-growth halo diameter was measured around the disk. In order to reduce errors, each test was repeated at least three times, and the mean non-growth halo diameter was measured on Mueller-Hinton agar and its antagonistic effect was investigated.

Results: The findings showed that adding a lactobacillus dose increases its inhibitory effects.The Lactobacillus plantarum were identified using specific primer pairs of the 16S rRNA gene, the established specific band, and PCR product sequencing. Rec A gene PCR was performed for differentiating the members of this group using specific primers and five Lactobacillus plantarum strains were identified.

Conclusion: According to the results of this study, lactobacilli were well able to inhibit the growth of pathogenetic strains. In this study, L. plantarum had an inhibitory effect on Escherichia coli.

Keywords: Lactobacillus, Escherichia coli, Antagonistic, PCR