Rahem E. Alziadi
This study was aimed to isolate and identify lactobacillus bacteria from some dairy products, antibiotic susceptibility and supernatants antimicrobial activity was tested, then detection for genes encoded to produce bacteriocins. morphological, microscopically and biochemical tests results showed that eight isolates were lactobacillus, antibiotic susceptibility test showed that most Lactobacillus isolates appeared multi resistant to more than one of antibiotics and sensitive to chloramphenicol while several of them are sensitive to others antibiotics , also results showed varying inhibitory effect of all Lactobacillus isolates supernatants in growth of pathogenic bacteria tastes, the highest inhibition zone that observed was against Escherichia coli O157:H7, Salmonella typhimiurum, Enterococcus faecalis, Clostridium spp, and Staphylococcus aureus, while weaker inhibition zone of Lactobacillus Isolates that observed was against Klebsiella sp and Pseudomonas aeruginosa,. DNA was extracted from isolates and PCR reaction was performed using primer specific for gene producing bacteriocins, this gene was produced PCR products with molecular weight ≈ 4000pb. The results showed that bacteriocins gene appeared in all lactobacillus isolates, therefore, such these Lactobacillus can be used as probiotic and as biopreservative in food.
Key words: Probiotics; Lactobacillus; Bacteriocins; Dairy products