In this study, isolation and identification of potential probiotic bacteria from traditional dairy products including yoghurt, cheese, curd and buttermilk from different regions of Azarbaijan, Iran was performed. Out of 48 traditional samples, 89 acid resistant isolates were screened from which 55 isolates represented high resistance to bile salts.

According to clustering based on biochemical assays, Lactobacillus isolates were grouped as: A: casei-maltaromicus- sakei, B: buchnerii- brevis- reouteri- fermentum, C: acidophilus- delbruchi- brevis, D: plantarum- agilis- morinuri and Enterococcus isolates were divided to a: fesium, b: fecalis and c: durans-hirae.

For further investigations, the isolates were studied based on 16S rDNA PCR -RAPD –ARDRA and Sequencing techniques. Based on restriction enzymes, group A and B, showed similarity to casei and brevis, respectively. Sequencing of three isolates attributed 2 isolates to brevis and 1 isolate to Lactobacillus sp.  Out of group C, the seperation of two isolates, acidophilus and delbruki, was approved by restriction reactions. Further, the restriction pattern similarity of five D group isolates to plantarum was conmfirmed by sequencing. From Enterococcus members, two isolates of group a, three isolates of group b and two isolates of group c were selected and sequenced.

Following the previous steps, cholesterol removal and antimicrobial activity of potential probiotic isolates were assessed. Based on cholesterol assimilation, the isolates were classified into three groups.  Fisrt group included 11 isolates related to Lactobacillus brevis, Lactobacillus casei, Enterococcus faecalis, Enterocccus sp and Lactobacillus sp with cholesterol assimilation of less than 100 µg.ml^-1. Second group included 61 isolates related to Lactobacillus casei, Lactobacillus brevis, Lactobacillus plantarum, Enterococcus faecium, Enterococcus faecalis and Enterococcus durans with cholesterol assimilation between 100 to 165 µg.ml^-1. Thirth group included 6 isolates related to Enteococcus facium, Lactobacillus plantarum and Enterococcus faecalis with cholesterol assimilation more than 165 µg.ml^-1. Antimicrobial activity of the isolates was determined against seven pathogens including Listeria monocytogenes, Klebsiella pneumoniae, Staphylococcus aureus, Escherichia coli, Shigella flexneri, Bacillus sereus and Yersinia enterocolitica. Inhibitory effects were evaluated in both natural and neutral pH conditions. The maximom inhibition in the isolates was against Listeria monocytogenes and the least was observed against Staphylococcus aureus. 32 isolates of Lactobacillus brevis and Lactobacillus plantarum showed inhibitory zone 1- 4.5 mm, 14 isolates of Lactobacillus casei the zone 2- 6.5 mm, 5 isolates of Enterococcus faecalis the zone 1-4 mm, 19 isolates of Enterococcus faecium and 4 isolates of  Enterococcus durans the zone 1-6 mm, the isolate Lactobacillus sp showed the zone 1-2 mm and the isolate Enterococcus sp showed the inhibitory zone 1-6 mm. In total, among Lactobacillus species, L. plantarum showed the highest cholestrol assimilation and L. casei showed the most inhibition against pathogenes. Among Enterococcus species, E. faecium and E. faecalis represented the highest cholestrol assimilation and E. faecium together with E. durans represented the highest inhibitory zone. The resulted data showed that traditional dairy products are valuable sources of probiotic microorganisms.