Isolation, Identification of Probiotic Lactobacilli from Traditional yogurts Produced in Rural Areas of Mazandaran province (Northern Iran)

Probiotic microorganisms are naturally present in milk and fermented milk products such as different kinds of yogurt, cheese, butter, etc. Probiotic bacteria are microbial food supplements with beneficial properties on human health. The objective of this study was the isolation of potentially probiotic Lactobacilli from traditional yogurt produced in rural areas of Mazandaran province (Northern Iran). In total, 40 samples of traditional yogurt were collected randomly from rural areas of Mazandaran province. The samples were aseptically weighed and homogenized. From each sample, a 1:10 dilution was subsequently made using peptone water followed by making a 10 fold serial dilution. The 0.1 ml from each dilution was then cultured, on MRS agar medium. Lactobacillus sp. was isolated from traditional yogurt samples, identified and characterized on the basis of their morphological and biochemical characteristics at genus level. The pure isolated Lactobacilli were assessed for various probiotic properties such as tolerance to acidic pH, bile salt, antibacterial activity. Out of the 40 traditional yogurt samples, 15 gram-positive, non-spore-bearing bacilli were identified at the first stage. At the next stages, 5 isolates of acid-stable and bile-stable lactobacilli were identified, including; Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus plantarum, Lactobacillus casei and Lactobacillus brevis.