University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 27 4 2016 11 01 Screening of Potentially Probiotic Lactobacillus Possessing Surface Layer Protein from Iranian Traditional Dairy Products 305 312 59336 EN E. Mobarak Qamsari Department of Microbiology, Faculty of Biology, Alzahra University, Tehran, Islamic Republic of Iran R. Kasra Kermanshahi Department of Microbiology, Faculty of Biology, Alzahra University, Tehran, Islamic Republic of Iran M. Erfan Department of Pharmaceutics, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Islamic Republic of Iran P. Ghadam Department of Biotechnology, Faculty of Biology, Alzahra University, Tehran, Islamic Republic of Iran Journal Article 2015 06 19 One of the most commonly observed surface structures on the prokaryotic cell envelopes is monomolecular crystalline array of proteinaceous subunits termed Surface Layers or S-layers. Due their self assembly ability and the highly ordered, regular structure down to the nanometer scale, S-layers were demonstrated to possess a great potential for nanobiotechnological applications. Some probiotic bacteria, such as <em>Lactobacillus</em> spp. have been found to possess S-layers. In this perspective, the objectives of this study were isolation and identification of <em>Lactobacillus</em> species from traditional dairy products carrying surface (S) layer protein and investigation of important prerequisite of probiotic interest, such as the capability to survive at low pH and in presence of bile salts.  The protein profile of intact <em>Lactobacillus </em>isolates was analyzed in SDS-PAGE. The protein bands of 45–60 kDa were present in two of the 25 isolates, suggesting the presence of S-layer proteins in these strains. The above mentioned proteins were recovered in the guanidine hydrochloride extracts. After dialysis, the extracted proteins showed a significant band of apparent molecular mass of 50–60 kDa in SDS-PAGE. The strains possessing S-layers protein was identified both biochemically and by 16S rRNA sequencing. The 16S rRNA gene sequence analysis revealed that two isolates exhibited maximum similarity with the 16S rRNA sequence of <em>Lactobacillus brevis</em> spp. These two isolates were resistant to acid and bile in which their viability in acidic condition were between 51.6% and 77.8% and bile resistance of two isolates was approximately 99% after 24 h. https://jsciences.ut.ac.ir/article_59336_71b67bf75e223a77f1a12baf4062dd2b.pdf