Debashis Halder and Shyamapada Mandal
Background and Objectives: Lactobacilli are used as probiotics, but scientific investigation of such strains is scanty. The current study aims to isolate and identify Lactobacillus strains from curd samples for probiotic characterization and antibiotic resistance determination.
Methods and Findings: Ten curd samples (homemade and commercially available) were screened for the presence of lactobacilli, and the isolates were identified by cultural methods, gram-staining and biochemical tests, and thereafter subjected to acid-, bile salt- and sodium chloride tolerance, and antibiotic susceptibility tests. Among 10 Lactobacillus strains, isolated one from each of the 10 curd samples, 2 were found as Lactobacillus fermentum (L. fermentum) and Lactobacillus casei (L. casei), which showed tolerance to bile salts (0.3%), low-pH value of 3, and low level of resistance to all the test antibiotics viz., ampicillin, chloramphenicol, cefotaxime, gentamicin and tetracycline, having MICs 8-32 μg/ml, except ciprofloxacin (MICs 2-4 μg/ml).
Conclusion: The findings of the current study meet the criteria, for the curd isolates of L. fermentum and L. casei, as being potential probiotic organisms, and curd, which is one of the highly-consumed dairy products, could be an important source of such probiotic bacterial strains.
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