Characterization of Lactobacillus isolated from dairy samples for probiotic properties

• Paper reports screening of 12 dairy isolates for standard probiotic properties.
• Isolate LBS2 identified as Lactobacillus rhamnosus with 16S rDNA sequencing.
• L. rhamnosus LBS2 successfully adhered to rat epithelial cells in in vitro conditions.
• In SEM study high surface roughness observed in LBS2 using in vitro high bile salt.

In the present study twelve Lactobacillus isolates (LBS 1-LBS 12) were characterized for probiotic properties. Out of the twelve, eight isolates (LBS 1–6, 8 and 11) were bile resistant (survival > 50% at 0.3% bile salt w/v) and five isolates (LBS 1, 2, 5, 6 and 11) were found acid pH value resistant (survival > 50% at pH 3). All twelve isolates inhibited the growth of Staphylococcus aureus whereas isolate LBS 2 also inhibited the growth of Escherichia coli and Salmonella typhimurium. Antibiotic susceptibility testing of isolates was also performed and isolate LBS 2 was selected for further study based on its broad spectrum effect in clinical pathogen inhibition. LBS 2 was characterized phenotypically at Institute of Microbial Technology (IMTECH), Chandigarh, India and was confirmed as Lactobacillus rhamnosus by 16S rDNA sequencing and subsequent analysis using BLAST. The gene sequence was deposited in GenBank with accession number KJ562858. Scanning electron microscopy (SEM) study was used to study in vitro epithelial cell adherence and bile salt effect on isolate LBS 2. Epithelial cells adherence assay showed positive results and surface roughness of LBS 2 increased with increase in bile salt (0.15–0.45% w/v).