DOI: 10.5176/2251-2489_BioTech25
Authors: Farzaneh Tafvizi and Maryam Tajabadi Ebrahimi
Abstract: Lactobacillus is one of the most important genera of lactic acid bacteria (LAB). Lactobacilli are naturally present in raw milk and traditional dairy products such as cheese, yoghurt and fermented milks or they are added intentionally in industrial dairy products to enhance the health quality and the potency of immunity system of the consumers. As the probiotic capacities are strain-dependent, methods for credible identification of lactobacilli at the strain level are very important, especially for the description of new strains. Conventional phenotypic and biochemical criteria often lead to ambiguous and time-consuming identification of the LAB. Therefore, the main focus has changed from phenotypic to genotypic methods because of more sensitive and accurate results. The aim of this study is isolation and identification of probiotic bacteria isolated from Iranian traditional dairy products to be potentially used for industrial ones. 17 strains were isolated from Iranian traditional yoghurt, cheese, whey and tarkhineh. Samples were grown in MRS broth and total genomic DNA was extracted. Detection of genetic diversity was made by RAPD markers. Out of 20 primers used, 19 primers produced reproducible bands. In total 273 bands were obtained out of which 273 bands were polymorph, 47 bands were unique in isolated studied. No common bands observed in genotypes. Different clustering methods (UPGMA and NJ) performed on molecular data produced similar results which was also supported by PCO ordination plot. c6c4 and y1m4 isolates show close relationship and grouped together with 100{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} bootstrap value in dendrograms. High similarly relationship observed between y1l4 and y2f3 is possibly due to isolation from the same source (yoghurt). Three populations of cheese, yoghurt and tarkhineh were considered for evaluation of genetic diversity based on Nei,s genetic diversity (H) and Shanon index (I). Data analysis showed the highest genetic diversity in yoghurt population.
Keywords: lactobacillus, genetic diversity, RAPD markers
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