Selective enumeration, isolation and identification of lactic acid and probiotic bacteria from locally available fermented and probiotic dairy products

This study was conducted to enumerate, isolate, characterize and identify the lactic acid bacteria (LAB) and probiotic bacteria in locally available fermented and probiotic dairy products. The ultimate objective was to preserve the isolates for their future potential use for developing new fermented and probiotic dairy products and for feed, pharmaceutical and other uses. Results of the study showed that the highest Str. salivarius ssp. thermophilus putative was obtained in Fruit Yogurt, 2.9 x 10 E20 CFU/g and lowest in Yogurt Natural, 2.6 x 10 E11 (P less than or equal to 0.01, CV=2.353%). Duo Yogurt was found to contain very high Lactobacillus delbrueckii ssp. bulgaricus putative count of 1.1 x 10 E9 CFU/g while Yogurt Drink had the lowest with 8.0 x 10 E7 CFU/g (P less than or equal to 0.05, CV=4.377%). Differences in counts were attributed to differences in manufacturing dates of samples used, although efforts were exerted to obtain samples manufactured within very close manufacturing dates. Probiotic bacterial putative count was highest in Yakult, 2.3 x 10 E8 while Neslac was the lowest, 1.6 x 10 E2 CFU/g (P less than or equal to 0.01, CV=2.890%). The nature of the product may have caused the differences in counts, Neslac being a powder. The lethal effect of processing and storage reduced the number of viable bacteria in dry milk. The viable counts of all the products, except Chamyto (plain), met the prescribed minimum viable count of 10 E5-10 E6 CFU/g for the consumer to obtain the claimed health benefits of consumption of probiotic dairy products. Identification of 28 isolates revealed the presence of five Lactobacillus acidophilus, four each of L. para. paracasel and L. delbrueckii delbrueckii, one each of L. brevis and L. delbrueckii bulgaricus. There were three Pediococcus pentosaceus and one each of P. damnosus and P. acidilactici. Of the probiotic bacterial isolates there were six Bifidobacterium sp. and two Actinomyces israelii