Isolation, Molecular Characterization, and Determination of Antibiotic Resistance Patterns of Lactic Acid Bacteria from Regional Yogurt Samples and their Probiotic Properties

This investigation aims to isolate the Lactic Acid Bacteria (LAB) from yogurt samples from the Tangail district of Bangladesh and evaluate their probiotic properties. Usual techniques of microbiological and biochemical process were used to identify them. A rigorous study was carried out from April to August, 2019. A total of 10 samples were examined by following the standard bacteriological methods. Besides the biochemical and antibiogram tests, molecular characterization of the isolated bacteria was carried out. Ten isolates were confirmed as LAB, and they exhibited excellent probiotic properties. They were able to survive in both acidic (pH 2) and alkaline (pH 8) conditions. They also survived against phenol (0.1-0.4%) and NaCl (1-10%) after 24 h incubation. Most of the isolates harboured plasmid DNA and showed good resistance patterns against the antibiotics used. During the mating experiment, no X-conjugants were found. In conclusion, the mating experiment suggested that the acquired resistant genes might be chromosome mediated, and isolates showed good probiotic properties that confer health benefits.