Isolation, biochemical and molecular identification of probiotic bacteria from traditional dairy products of Sabzevar

Probiotics are beneficial and non-pathogenic microorganisms. Isolation of probiotic bacteria from traditional dairy products can not only lead to the isolation of probiotic bacteria with special characteristics، but it can offer a good approach for the mass production of traditional dairy products containing natural probiotic bacteria. After collection of dairy products samples from different regions of Sabzevar، they were continuously cultured on the specific media of MRS and MRS Broth. Initial identification of isolates was performed by gram stain، motility test، nitrate reduction test، growth at 15 and 45 °C، growth at pH: 9/6 and fermentation capability of 11 different sugars. To identify desired strains more precisely، the 16S rDNA gene was amplified by PCR with specific primers and then sequenced and BLASTed. Acidic and bile salts conditions tolerance tests were performed for the final confirmation of desired strains. After continuous culture on specific agar media، 16 strains for further analysis were selected. In early identification of isolates by phenotypic methods، 14 strains were positive. To identify these strains more precisely، the 16S rDNA gene was amplified. Following molecular identification and sequencing of 16S rDNA gene، the BLAST sequence similarities were found with Lactobacillus planetarium. In addition، acidic and bile salts conditions tolerance tests showed that these bacteria had the best growth pattern at PH: 4 and they were able to grow in the presence of bile salts. Biochemical results showed that the most common strains in the tested dairy products are Lactobacillus. These results also confirmed by the molecular tests. Acidic and bile salts conditions tolerance test، as a main characteristic of probiotic bacteria، showed that the strain was able to withstand these conditions.