Isolation and identification of probiotic Lactobacillus from local dairy and evaluating their antagonistic effect on pathogens

Abstract

Objective: Probiotics such as lactobacilli prevent the development of a wide range of human and animal's pathogens. The aim of this study was evaluation of antagonistic effect of isolated lactobacilli from local dairy products against three standard strains of Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. Materials and Methods: Twenty samples of local dairy products including cow milk, buffalo milk, cheese and yogurt were collected from different areas of Ahwaz city. Antimicrobial disc diffusion method was applied on S. aureus (ATCC-6538), B. subtilis (ATCC-12711) and P. aeruginosa (ATCC-27853). Antimicrobial effects of isolates were evaluated by disc diffusion test on Mueller-Hinton agar medium plated with three pathogens. Results: Obtained results showed that only three strains of isolated lactobacilli of local dairy samples had inhibitory effects on understudy pathogens including Lactobacillus alimentarius, Lactobacillus sake and Lactobacillus collinoides. All three isolates showed moderate activity (inhibition zone <15 mm) except of L. collinoides and L. alimentarius that had relatively strong activity (inhibition zone ≥15 mm) against P. aeruginosa and B. subtilis, respectively. Conclusion: These bacteria can be raised for the production of various kinds of food, pharmaceutical products and functional foods.