PROBIOTIC POTENTIAL AND STRESS TOLERANCE IN LACTOBACILLUS MU1008 ISOLATED FROM CHILLED YOGURT SAMPLES OF MAJMAAH

In recent years, scientific research has confirmed the presence of large amounts of probiotic Lactobacillus sp. in fermented dairy products, which shows a positive impact on human health. This study was designed to isolate Lactobacillus with probiotic potential from local and commercial samples. 40 Lactobacilli strained were isolated from commercial and local yogurt samples by tenfold dilution plating method and plated on Man-Rogosa-Sharp agar medium and were screened for their use as potential probiotics. The isolates were tested for their ability to survive at pH 2.0, pH 3.0, in the presence of 0.3% bile salt and antimicrobial activity; sensitivity against 10 specific antibiotics (ciprofloxacin, erythromycin, tetracycline, penicillin G, ampicillin, streptomycin, polymyxin B, vancomycin, chloramphenicol and rifampicin) using filter paper disc diffusion method and two-fold serial dilution methods. Out of the 40 strains, 24 strains (42%) had survival rates above 90% after 2 h of incubation at pH values of 2.0 or 3.0 pH. Further screening performed on the above 40 isolates indicated that 24 strains show to 0.3% bile salt. Lactobacilli strains exhibited inhibitory activity against Salmonella strains and Candida albicans. Moreover, all of the strains were resistant to vancomycin and streptomycin. The 24 strains that were found suitable for Potential probiotic activity including strains Lactobacillus casei (95%), Lactobacillus salivarius (25%), Lactobacillus plantarum (75%), and Lactobacillus buchneri (72%).