Analysis of Probiotic Properties of Isolated Bacteria from Selected Yogurts and Poultry Feces

Abstract

Lactic acid bacteria (LAB) are beneficial probiotic organisms that provide to improved microbial balance, nutrition, and immune-enhancement of the intestinal tract, as well as lower cholesterol. In the present study four different yogurts and two poultry feces were used. The phenotypic and biochemical analyses gave a diversity of four presumptive species viz. Lactobacillus acidophilus, Streptococcus thermophilus, Lactobacillus brevis, and Bifidobacterium spp from yogurt sample and three presumptive species viz. Lactobacillus acidophilus, Lactobacillus brevis, and Bifidobacterium spp. were found from two poultry feces sample respectively. The result was identified by their morphological, physiological and biochemical assay. It was observed that all the four species were gram positive, endospore negative, catalase negative and non-motile which are the characteristic to typical probiotic bacteria. Carbohydrate/sugar fermentation profiles experiment using sixteen important sugars ensured the presumptive identification of isolated species. The results showed that, the all selected species were resistant to artificial gastric juice environment at pH 2.2 and 6.6 but their resistance capacity decreased after 24 hours of incubation at 37°C. They showed excellent tolerant ability to phenol and bile salt concentration. The NaCI tolerance test results of the isolated probiotic bacteria have shown that all the isolates have excellent tolerance against 1•6% NaCl, moderate in 7% to 9% and in 10% NaCI, no growth was observed after 24 hours of incubation at 37°C. Moreover, all the isolates showed bile salt hydrolase activity using bile salt plate on solid MRS medium containing 0.5% taurodeoxycholic acid by forming opaque granular white colonies characteristic to probiotic lactic acid bacteria. Isolated bacteria from both yogurt and poultry feces were able to coagulate milk when 1% (v/v) culture of probiotic bacteria was inoculated into sterilized skim milk and incubated for overnight. In vivo culture experiments were performed by using Seven weeks old Swiss Albino mouse. Twenty four mice were used to investigate the effects on cholesterol level, antibiotic resistance ability, and inhibiting growth of pathogenic bacteria. For in vivo experiments, 12gm of yogurt made by selected bacterial cultures were orally administered to rats every day up to 4 weeks which showed reduced cholesterol levels significantly (p < 0.05), and antagonistic activity against potential pathogenic bacteria, the treatment group receiving probiotic bacteria showed significant resistance to the antibiotic which indicates that the isolated strains are potential for probiotic use.