Microbiology

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    Antioxidant Activities of Exopolyscharides Produced by Lactic Acid Bacteria Isolated from Commercial Yoghurt Samples
    (Bells University of Technology, 2019-09-16) EZEANI, Abiola olufadeke; Dr.(Mrs) A.O. Adelekan
    Antioxidant is a substance that inhabit the oxidation of other molecules caused by free radical. The inbuilt antioxidant system possessed by living organism are generally not enough to prevent them from oxidative here and for damages and the use of synthetic antioxidants also have some harmful effect. This provide the need to search for more antioxidants from natural sources.Therefore,this study was aimed at evaluating the antioxidant activities of exopolysaccharides produced by lactic acid bacteria isolated from yoghut.Lactic acid bacteria (LAB) were isolated from six different brands of commercially available yoghurt using deMan Rogosa shape (MRS) agar.The LAB isolated were identified based on morphological, biochemical as well as molecular characterizations and were screened for exopolysaccharides (EPS) production. The LAB isolates screened positives were used for EPS production in a liquid medium and the EPS produced were purified and quantified using standard cmethods.Antioxidant activities of the EPS were evaluated by determining the DPPH fess radical scavenging activity, ferric ion reducing power and total phenolic contents. Data obtained were analyzed using Analysis of Variance.Total latic acid bacterial count obtained from the yoghut sample ranged from 0 - 3.9 10 CFU/mL with sample A (Fan Yoghurt) having the highest LAB count (25.49%), L delbrueckii (19.61%), L fermentum (15.69%), L, acidophilus (13.73%), Leuconostoc mesenteroides (11.76%0 Lactococous lactis (7.84%) and Lactobacilus caseil (5.88%).Fifty - one of thr 64 LAB isolated were screen positive for EPS production and only six were able produced susbtantial were quantity of EPS ranging from 127.7 - 208. mg/L..Based on molecular charactrerzation, the four highesr EPS - producing LAB isolated were identified as Lactobcillus plantarum (208.5 mg/L).