Identification and Characterization of Lactobacillus Isolates Recovered from Locally Fermented Milk (Nunu) consumed within Lagos Metropolis

ABSTRACT

This work assessed the probiotic potential of “Nunu” using Lactobacillus, a genus of Lactic acid bacteria and a major probiotic organism as the indicator. The viable Lactobacillus counts of samples purchased from six different areas within Lagos Mainland were enumerated by serial dilution and pour plating in selective media, DeMann, Rogosa and Sharpe agar (MRS). Twelve strains of Lactobacillus were randomly selected from the samples and identified by standard morphological, physiological and biochemical methods. The isolates were identified as L. casei, L. bulgaricus, L. acidophilus, L. plantarum, L. rhamnosus, L. thermophilus, L. reuteri, L. helviticus, L. delbrueckii, L .brevis. L. cellobiosus, L. fermentum with L. acidophilus occurring the most and elicited the highest count of 421.2 x 106 cfu/ml while L. reuteri has the lowest count of 2.5 x 106 cfu/ml. This indicates that L. reuteri probiotic level is been compromised by count. The isolates were further examined for bacteriocin like activity against E.coli ATCC25922 using agar well diffusion method. After incubation, the zones of inhibition was observed and recorded. Locally fermented milk of probiotic value has bacteriocinogenic property against E.coli although it carries resistant plasmid which can serve as drug resistance when consumed.

Keywords: Characterization, Fermentation, Identification, Incubation, Lactic Acid Bacteria (LAB), Lactobacillus, Milk, Nunu.