Evaluation of Probiotic Potentials of the Lactic Acid Bacteria (LAB) Isolated from Raw Buffalo (Bubalus bubalis) Milk

Abstract

Received: Revised: Accepted: Published online: November 28, 2018 December 20, 2018 December 22, 2018 January 24, 2019 Lactic acid bacteria are widely used as probiotics to produce and preserve foods. This study aimed to isolate and evaluate probiotic potentials of lactic acid bacteria from raw buffalo milk. The bacterial colonies (n=130) were isolated from 30 randomly collected raw buffalo milk samples. Based on morphology and biochemical tests, twenty isolates were identified as lactobacilli and evaluated for tolerance to pH (2, 3, 4.5, 6.5), bile (0.5, 1% w/v) and lysozyme (50 and 100 μg/mL). Five out of twenty lactobacilli isolates showing highest resistance towards acid, bile and lysozyme were selected for further probiotic characterization. Tests for tolerance to gastrointestinal fluids, adhesion characteristics, antibiotic susceptibility, hemolytic activity, antibacterial activity, β-galactosidase activity, exopolysaccharide production and heat resistance were performed. The survival of the isolates in simulated gastric fluid and simulated intestinal fluid ranged from 6.60-7.03 Log CFU/mL and 8.36-8.74 Log CFU/mL respectively. The isolates showed autoaggregation (14-62%), hydrophobicity (11-55%) and adhesion to Caco2 cell lines (21-60%). The lactobacilli isolates were positive for β galactosidase activity, exopolysaccharide production, heat resistant and negative for hemolysis. Isolates were susceptible to most of the tested antimicrobial agents and showed antimicrobial activity against all tested food borne pathogens. The isolates were identified through 16S rDNA sequencing as Lactobacillus plantarum, Lactobacillus pentosus, Lactobacillus fermentum and Lactobacillus reuteri. All isolates produced probiotic based yogurt and survived in cold storage (4°C) after 28 days. The results suggest that isolated probiotics have potential use for the development of fermented food products. ©2018 PVJ. All rights reserved