Evaluation of Probiotic and Antimicrobial Properties of Lactobacillus Strains Isolated from Dairy Products

Objective: Evaluation of antimicrobial efficacy of probiotic Lactobacillus strains isolated from dairy products. Methods: The study used yogurt sample prepared from raw buffalo milk to isolate Lactobacillus strains by following pour plate technique. All isolated Lactobacillus strains were systematically screened for their probiotic attributes. Here, functional criteria studies for successful probiotics mainly included survival ability of the strains. The capability of the selected Lactobacillus isolates to inhibit the growth of several pathogens was evaluated by the well diffusion method. Based on phenotypic characteristics, biochemical tests and of 16S rDNA sequence analysis, the potent probiotic strain was identified. Further study was emphasized on its optimum parameters required for its growth. Again, its activity was characterized with respect to pH, NaCl and thermal stability along with susceptibility to enzymes. Results: A preliminary subtractive screening based on antimicrobial potency and probiotic properties revealed the maximum effectiveness of Lactobacillus DM 69 among all and it was identified as Lactobacillus plantarum. The inhibitory substance obtained from DM 69 was relatively heat stable and active under acidic conditions. No susceptibility was found in the presence of α-amylase, lipase and lysozyme. Conclusion: Excellent probiotic and an antimicrobial strain was isolated from buffalo milk and can be formulated and developed as a good nutraceutical food supplement.