Detection of genetic diversity of lactobacillus

Aim and background. The genus Lactobacillus encompasses a diverse assemblage of Gram-positive، catalase-negative، non-spore-forming، rod-shaped organisms. Over 90 species are currently described. Several strains of probiotic lactobacilli have been incorporated in a wide range of products for human. As the probiotic capacities are strain-dependent، methods for reliable identification of lactobacilli at the strain level are of great importance. Regarding biochemical methods are time-consuming and often very ambiguous the molecular methods are more accurate. The aim of present study is typing of lactobacillus species isolated from different traditional dairy products by RAPD markers. Materials and Methods. The 20 strains used in this study were isolated from different sources. Samples were grown in MRS broth then total genomic DNA was extracted. RAPD markers were used for the detection of genetic diversity. Results. Out of 20 primers used 19 primers produced reproducible bands. The primers generated 225 RAPD loci، of which 219 were polymorph، 6 were monomorph and 63 were unique. NJ and UPGMA clustering methods performed on molecular data by NTSYS-PC software. Similar results are obtained by two methods. Conclusion. UPGMA clustering methods were performed on molecular data. Two genotypes of k2l3 and y1m4 are grouped together in two dendrograms. In UPGMA dendrogram two major clusters A and B were observed. Cluster A was divided in to2 subcluster by c6m3، y1l4، y2f3 and c1d2 genotypes. In cluster B، 2 subclusters by 6 genotypes (c2h1، d3b1، y2c4، k2l3 و y1m4 and p) were observed.