REP PCR CHARACTERIZATION OF LACTIC ACID BACTERIA ISOLATED FROM SHEEP'S MILK IN ALGERIA AND ASSESSMENT OF THEIR PROBIOTICS POTENTIAL

摘要

Lactic acid bacteria (LAB) found in many environments ranging from fermented foods to the mammalian gastrointestinal tract. The aim of the present study was to isolate and identify coccoid lactic acid bacteria from raw sheep's milk using a combinationof pheno-and genotypic methods, including (GTG) 5-based rep-PCR fingerprinting, 16Sr RNA gene sequencing and carbohydrate assimilation profiling. Further, basic traits for potential probiotics screening such as tolerance of acidity and 0.3% concentration of bile salts, antimicrobial susceptibility antibacterial activity, and hemolysis was assessed. Using molecular biology-based methods and selected phenotypic tests such as catalase reaction, C02 production from glucose, colonies, and cells morphology and fermented particular sugars, the twenty two isolates were identified as En terococcus faecium, Enterococcus faecalis and Streptococcus ihermophilus. The selected isolates were grown in acidity at pH 2 and survival in bile salts of 0.3% concentration and were resistance to some antibiotics such as chloramphenicol, vancomycin, tetracycline, gentamicin, penicillin G, and sensible to another. They inhibited several pathogenic bacteria including Listeria monocytogenes, Escherichia coli, Staphylococcus aureus and no hemolytic activity was observed.