The relationship between the sources of lactobacillus isolates and their antimicrobial activity

Abstract

Lactobacillus genus was isolated from two different sources, healthy infants feces and some dairy products, identify isolates by traditional methods, and confirm a diagnosis by molecular detection. Susceptibility was tested to some antibiotic, then supernatants antimicrobial activity was tested against some pathogenic bacteria involved Escherichia coli O157: H7, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Klebsiella sp., Salmonella typhimiurum, and Clostridium sp. Morphological, Microscopically, and Biochemical test results showed that eleven isolates were lactobacillus, DNA was extracted from isolates, and polymerase chain reaction (PCR) reaction was performed to confirm the diagnosis using a specific primer for 16SrDNA in Lactobacillus genus, Lacto F and Lacto R, all isolates gave PCR products with molecular weight 231bp. Antibiotic susceptibility test showed that Lactobacillus isolates of healthy infants feces have appeared as multi-resistant to more than one of antibiotics and sensitive to chloramphenicol. While Lactobacillus isolates of dairy products were less resistance to antibiotics, and most of them were sensitive to antibiotics. Also, results showed the varying inhibitory effect of all Lactobacillus isolates supernatants in the growth of pathogenic bacteria in this study; healthy infants feces isolates showed the highest inhibition zone than dairy products Lactobacillus isolates.