Antibacterial activity and cholesterol assimilation of lactic acid bacteria isolated from traditional Iranian dairy products

In this study, lactic acid bacteria were isolated from ewe milk, traditional yoghurt and sour buttermilk samples collected from different areas of Azarbayjan-e-sharqi in Iran. All the isolates were screened for their ability to produce bacteriocin like inhibitory substances (BUS) by studying their inhibitory action against pathogens like Listeria monocytogenes, Salmonella enteritidis and Staphylococcus aureus, after eliminating the effect of organic acids and hydrogen peroxide. According to results, four of the isolates identified as Lactobacillus brevis, Lactobacillus pentosus, Pedoicoccus acidilactici and Lactobacillus paracasei were unaffected by the action of pH neutralization and hydrogen peroxide and showed inhibitory action against the tested pathogens. The inhibitory activities demonstrated by these isolates were completely inhibited in the presence of proteolytic enzymes. The isolates in study were further characterized for their cholesterol reduction ability. Cholesterol assimilation by both viable and dead cells of these strains was determined in MRS broth containing 0.3 g/100 mL bile salt. According to results, highest level of cholesterol removal was recorded in L brevis, while all the other isolates in study were also able to reduce cholesterol to lesser extent. To conclude, the Lactic Acid Bacteria isolated from these traditional products might be exploited for their probiotic potential for future studies. (C) 2013 Elsevier Ltd. All rights reserved.