IN VITRO SCREENING OF LOCALLY ISOLATED LACTOBACILLUS SPECIES FOR PROBIOTIC PROPERTIES

The present study was conducted to determine the probiotic properties of locally isolated lactobacilli in-vitro conditions. For this purpose, intestinal contents (n=20) were collected from crop, gizzard, ileum and caecum of adult healthy chicks and conventional yogurt samples (n=20) were procured from the local market for the isolation of lactobacilli. These samples were mixed homogeneously in sterilized phosphate buffer saline (PBS) separately. Samples from both sources were inoculated on deMan Rogosa and Sharpe (MRS) agar. L. acidophilus 3, L. rhamnosus and L. salivarius were isolated from intestinal contents, while L. delbrucekii ssp bulgaricus and L. paracasei ssp paracasei 1 were isolated from yogurt samples. These lactobacilli were identified through standard API-50 CHL system and then screened for resistance against bile salt, acidic pH, gastric transit and ability to inhibit pathogens as well as survival under different storage temperatures. Tolerance level was found variable (P<0.05) among all the tested species of lactobacillus. All the tested species, except L. delbrucekii and L. paracasei, showed good survival (P<0.05). All lactobacilli inhibited the growth of E. coli and Staphylococcus aureus, except L. delbrucekii that showed significantly (P<0.05) low antimicrobial effect. The results showed that L. acidophilus 3, L. rhamnosus and L. salivarius fulfilled the criteria of in-vitro screening for probiotic properties