Isolation and Biochemical Characterization of Lactobacillus species Isolated from Dahi

Abstract

Dahi (curd) is a fermented milk product, most commonly used by Indian population. Trials are in process to establish dahi as a source of health beneficial organisms (probiotics). Hence, the present study is directed towards the study of prevalence of Lactobacillus species in dahi . A total of 40 samples of dahi were collected for the isolation of Lactobacilli using Lactobacillus selection MRS agar. Thirty-eight colonies were randomly picked based on colonial morphology. All the isolates were subjected to cell morphology, physiology and an array of biochemical characterization. The isolates showed different growth patterns at different temperatures (15 ° C and 45 ° C), oxygen and at different concentrations of NaCl (2.0, 4.0 and 6.5%). On the basis of physiological tests and sugar utilization pattern, all the seventy-eight isolates were confirmed to the different species of Lactobacillus: Lactobacillus casei (24.35%), Lactobacillus brevis (3.84%), Lactobacillus fermentum (6.41%), Lactobacillus plantarum (7.69%), Lactobacillus helveticus (5.12%), Lactobacillus rhamnosus (6.41%), Lactobacillus viridiscence (5.12%), Lactobacillus lactis (3.84%), Lactobacillus acidophilus (37.17%). Among isolates, L. acidophilus was found to be prevalent in dahi. Keywords: Dahi, probiotics, biochemical characterization, MRS agar