Isolation and Identification of Indigenous Lactic Acid Bacteria from Traditional Yogurt Produced from Ewe's Milk from Alvand Nomads Region and Evaluation of Their Acidifying Potential

The aim of this study is identification of lactic acid bacteria from ewe’s yogurt from alvand nomads and evaluation of acidifying potential of isolates. A total of 25 bacteria as lactic acid bacteria were isolated from ewe’s yogurt. The log10 CFU of bacterial count per ml of yogurt on MRS, M17 and Corn meal agar under anaerobic condition at 37 0C included 5.84 ±0.14, 4.69± 0.21 and 5.95± 0.06 respectively. To identify the strains isolated, they were tested by examining their cell morphologies, gram-staining, catalase activity, arginine hydrolase activity and carbohydrate fermentation. Isolates of yogurt Produced from Ewe's Milk were identified on the basis of biochemical and phenotypic characteristics as Enterococcus faecium, Enterococcus durans, Pediococcus acidilactici, lactobacillus paraplantarum, lactobacillus ferintoshensis, lactobacillus johnsonii and lactobacillus delbrueckii. Acidification activity of isolates was assessed. lactobacillus delbrueckii (ΔpH3h=0.65), lactobacillus ferintoshensis (ΔpH3h=0.6) and Pediococcus acidilactici (ΔpH3h=0.57) showed more acidifying activity than other isolates, respectively. Acid production profiles of isolates indicated that these isolates could lower the pH of milk below 5±0.2 in 6 h incubation at 30 °C and these isolates were therefore the best starter candidates for industrial applications.