Mining of lactic acid bacteria from traditional yogurt (Mast) of Iran for possible industrial probiotic use

Lactobacillus is a genus of gram-positive bacteria of high probiotic value. The bacteria of this genus are responsible for maintaining and promoting the microbial balance of the human gut, where they along with promoting better digestion and absorption, also help in suppressing many infectious diseases. Iranian traditional yogurt (Mast) is a rich source of Lactobacillus microorganisms and their identification can be explored for their use in industrial probiotics. This study is aimed at isolation and identification of different Lactobacillus strains present in the Mast. Forty samples of Mast from eight different regions of the Iran were cultured in De Man, Rogosa and Sharpe agar (MRS) media for isolation. The isolated strains were identified by morphological and biochemical methods using gram staining, catalase, oxidase, motility and indole tests. For biochemical identification, the isolates were subjected to carbohydrate fermentation test using phenol red broth base. Overall eight strains were majorly identified based on biochemical and morphological screening which were further confirmed using 16S rDNA-based identification. Two strain of Lactobacillus acidophilus, two strains of Lactobacillus bulgaricus, two strains of Lactobacillus delbrueckii and two strains of Lactobacillus casei were identified. Lactobacillus delbrueckii subsp. Bulgaricus isolated from Bushkan showed higher bile salt resistant activities (18.92, 13.56 and 10.22%) than that of the available Lactobacillus bulgaricus strain (3.08, 1.87 and 1.44%) in 0.3, 0.5 and 1.0% bile salt. This study thus provides insights into probiotic potential of Mast which could be explored in industrial yogurt and cheese production.Highlights Insight into Lactic Acid Bacteria profile of traditional yogurt of Iran. The Lactic Acid Bacteria profile varies from region to region. Proposes possible probiotics for commercial yogurt production from traditional yogurt of Iran