IDENTIFICATION AND CHARACTERIZATION OF LIMOSILACTOBACILLUS FERMENTUM ISOLATED FROM KANGRA CURD

Abstract

Curd, commonly called “Dahi," is a fermented milk product widely consumed in India for its probiotic benefits. The composition of the probiotic strains in curd varies with geographical location. This study aimed to identify the most predominant strain of Lactobacillus in the curd collected from Chhattri village, Shahpur tehsil, Kangra district, Himachal Pradesh. The sample was inoculated in MRS broth and streaked on the MRS agar plate. The most prevalent isolate was characterized on morphological, biochemical, and molecular bases. Comprehensive analysis, including Gram staining, catalase test, oxidase test, motility test, and indole test, as well as evaluations of pH, bile, salt, and temperature tolerance was performed. The isolate was gram-positive, catalase, oxidase, sulfide, and indole-negative. It showed maximum growth at 0.5% salt, 0.5% bile salts, and 37ºC. Optimal growth occurred between pH 6-8, with peak growth at pH 7. Molecular identification and phylogenetic analysis confirmed the isolate as an L. fermentum strain. This strain exhibited the highest prevalence in Kangra and showed promising probiotic traits with potential gastrointestinal health benefits. Its dominance highlights the probiotic richness of curd obtained from the lower hills of Himachal Pradesh.