Journal of Pure and Applied MicrobiologyVol. 2 No. 2

Isolation of Bile Tolerant Lactobacilli and Their Biochemical Characterization

Khushbu Singhal*, Harshada Joshi and B.L. Chaudhary

Department of Biotechnology, Vigyan Bhawan Block B: New Campus, Mohanlal Sukhadia University, Udaipur, India.

Received on 17 April 2008 and accepted on 24 July 2008



A total of 140 strains of lactobacilli were isolated on MRS agar medium supplemented with 0.2% of sodium taurocholate and 0.2% of sodium thioglcocholate from 10 samples comprising of 4 samples of cow milk, 4 samples of curd, and 2 samples of camel milk. Among 140 strains 36 were isolated from cow milk, 12 from camel milk and 92 strains were isolated from curd samples. The isolated strains were identified on the basis of their cultural, morphology, and biochemical characteristics. Among the 140 isolates, only 68 isolates showed positive characteristics of genus Lactobacillus. A total of 82 of them showed precipitation of deoxycholic acid which was diffused in the surrounding medium. All of them showed gram- positive reaction, growth at 15 0C temperature, white colonies on MRS agar medium and produced yellowish colonies on BCP agar medium. All the 68 isolates showed negative test for catalase, no growth at 45 0C temperature and no gas production from glucose. Among the 68 isolates 35 isolates reduced litmus milk fast whereas 33 isolates were quite slow in this reaction.

Keywords : Lactobacillus, isolates, biochemical reactions.