Abstract

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Probiotics are non-pathogenic and non-toxigenic bacteria that serve as a natural barrier against pathogenic enteric bacteria. Yoghurt and other fermented dairy products are the most common source of probiotics.This study was carried out to assess the probiotic potential of Lactobacillus species isolated from different brands of yoghurt. Nine(9) yoghurt samples consisting of three (3) different brands were purchased from local vendors. The samples were serially diluted, inoculated onto De Man Rogosa and Sharpe(MRS) Agar and incubated anaerobically using a candle jar at 37oC for 24 hrs. Colonies with characteristics colonial morphology of Lactobacillus species on MRS agar were sub-cultured fresh MRS agar. The isolates were further identified and characterized microscopically and biochemically. The isolates were screened for their ability to tolerate low pH, tolerate bile and exhibit antibacterial activity. The nine (9) isolates of Lactobacillus species obtained consist of 7(77.78%) L. plantarum, 1(11.11%) L. bulgaricus and 1(11.11%) L. salivarius. All the isolates tolerated low pH and bile salt at different concentrations. Two (2) of the isolates had antibacterial activity against Escherichia coli, however none of the isolates had antibacterial activity against Salmonella Typhi. Of the three Lactobacillus species isolated from yoghurt, L. plantarum had the highest occurrence with 77.78%.Two of the Lactobacillus species isolated from yoghurt tolerated low pH, bile salt at different concentrations and exhibited antibacterial activity hence possesses probiotic potential.

Keywords: Lactobacillus species, probiotic, yoghurt, antibacterial