غربال انتخابي لاكتوباسيل‌هاي بالقوه پروبيوتيك از محصولات لبني تخميري محلي

Selective screening of potential probiotic Lactobacilli in traditional fermentative dairies

Traditional fermentative dairy products are complex ecosystem of lactic acid bacteria and because of this microbial variety, direct isolation of probiotic from traditional dairy products is very complicated operation. Aim of this study was to selective screening of potential probiotic lactobocilli from traditional dairy products including yoghurt, cheese, and dried whey without passing through preliminary time consuming isolation steps. In this study, 30 different samples of diary products were prepared from traditional workshops and following the delivery to laboratory in 4°C, they carried to MRS broth that is considered as a suitable nutritive medium for incubation of lactobacilli. In order to increase the possibility of probiotic bacteria growth, dairy samples went through an acidic treatment and then the species sensitive to acidic condition were omitted and the isolates which were resistant to acid and bile salts were separated on a MRS agar medium containing 1% bile salts. Following the warm coloration and catalase test, the positive warm bacilli and lactobacilli negative catalase were identified and stored under glycerol in -70°C and their resistance to acidic condition and bile salts were evaluated. Finally, from among 30 different dairy samples, 19 lactobacilli species which had the highest resistance to acidic condition and bile salts were chosen as the potential probiotic species.