Isolation and Characterization of Lactobacillus Strains from Different Samples for Their Potential Probiotic Activity by Nikita, Garg, Bhardwaj, Richa, Yadav, Ruchik

Abstract: Isolation of Lactbacillus strains was done from four samples namely – milk and dung (of cow); fodder and soil (of cowshed). Pure cultures were obtained from the diluted samples by recurrent streaking on de Mann Rogosa Sharpe Agar (MRS) medium. The identity of the cultures was based on characteristics of the strains of lactobacillus spp. as presented in the Bergey‘s Manual of Determinative Bacteriology, carrying out microscopy (morphology), gram-staining, catalase test and fermentation of different carbon sources. On the basis of all the identification tests and confirmation by GC-FAME analysis, three strains isolated were identified as Lactobacillus delbruekii, Lactobacillus lactis and Bacillus cereus. The identified lactobacilli were screened for their probiotic activity by testing for various parameters - Bile salt tolerance, pH tolerance, Anti- microbial activity by Agar well- diffusion method and Antibiotic resistance by Disc – Diffusion Assay. The results were compared with the values obtained for the standard reference probiotic strains Lactobacillus casei and Lactobacillus acidophillus. Inherent â-Galactosidase enzyme activity of all the Lactobacillus strains was checked and protoplast fusion was attempted.