Isolation of Probiotic Lactobacilli from Traditional Yogurts Produced in Rural Areas of Rafsanjan and their Antimicrobial Effects, 20012

Probiotic bacteria are microbial food supplements with beneficial properties on human health. The increase in the use of industrial dairy products instead of the traditional ones may enhance the possibility of missing the probiotic bacteria. The aim of this study was to isolate lactobacilli from local yogurts produced in rural areas of Rafsanjan and also to investigate their antibacterial effects against four common pathogenic bacteria. In this laboratory study، 40 samples of traditional yogurts from four separated rural areas were collected. Probiotic lactobacilli were isolated using MRS medium، selective screening methods، catalase test، and some relevant biochemical tests. Bactericidal effects of the isolated probiotics against S. Aureus، E. cloi، S. pyogenes، and P. vulgaris were investigated using disk diffusion and well diffusion agar methods. Out of the 40 local yogurt samples، 33 isolates of acid-stable lactobacilli were selected at the first stage. At the next stages، 9 isolates of acid-stable and bile-stable lactobacilli were isolated including; L. Casei (in two places) L. rhamnosus L. plantarum L. acidophilus، L. Bulgaricus، L. delbrueckii، L. fermentum، and L. brevis. While the growth of the 4 pathogenic bacteria was suppressed by all 8 lactobacilli، L. plantarum showed the strongest bactericidal effects. Traditional yogurts may possess probiotic bacteria with antibacterial properties. These probiotics can be used for mass production of industrial dairy producs.