An antioxidant is a substance that inhibits the oxidation of other molecules caused by free radicals. The inbuilt antioxidant systems possessed by living or g anisms are generally not enough to prevent them from oxidati ve damage s and the use s of synthetic antioxidants also ha ve some harmful effects. T his study was aimed at evaluating the antioxidant activities of exopolysaccharides p roduced by lactic acid bacteria isolated from yoghurt. Lactic acid bac teria (LAB) were isolated from six different brands of commercially available yoghurt using deMan Rogosa Sharpe (MRS) agar. The LAB isolates were identified based on morphological and biochemical analyses and were screened for exopolysaccharide (EPS) production. The LAB isolates screened positive were used for EPS production in a liquid medium and the EPS produced were purified and quantified using standard methods. Antioxidant activities of the E PS were evaluated by determining the 1,1-dip henyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, ferric ion reducing power, and total phenolic contents. Data obtained were analysed using Analysis of Variance. Total lactic acid bacterial count obtained from the yoghurt samples ranged from 0 - 3.9 × 10 4 CFU/mL with sample A (Fan Yoghurt) having the highest LAB count (3.9 × 10 4 CFU/mL). The isolated LAB and their incidence rate were Lactobacillus plantarum (25.49%), L. delbrueckii (19.61%), L. fermentum (15.69%), L. acidophilus (13.73%), Leuconostoc mesenteroides (11.76%), Lactococcus lactis (7.84%), and Lactobacillus casei (5.88%). Fifty-one out of the 64 LAB isolates were screened positive for EPS production and only six were able to produce substantial quantity of EPS ranging from 127.4 - 208.5 mg/L. The exopolysaccharides produced by L. fermentum had the highest DPPH radical scavenging activity (62.90%) while that of L. plantarum had the lowest (23.10%) at a concentration of 1000 μg/mL. Also, the EPS produced by L. fermentum recorded the highest ferric ion reducing power (12.89 mg AAE/mL) at 1000 μg/mL while that of L. plantarum had the lowest (5.62 mg AAE/mL). At 1000 μg/mL, the total phenolic contents of the EPS samples ranged from 1.41 - 1.58 mg GAE/mL, and the EPS produced by L. fermentum had the highest (1.58 mg GAE/mL) while those produced by L. paracasei had the lowest (1.41 mg GAE/mL). This study revealed that the exopolysaccharides produced by the LAB isolates showed high antioxidant activities with respect to their DPPH free radical scavenging activity, ferric ion reducing power and total phenolic contents.
El-Said, M.M., Haggag, H.F., Fakhr, H.M., El-Din, H.F.M., Gad, A.S. and Farahat, A.M. (2014) Antioxidant Activities and Physical Properties of Stirred Yoghurt Fortified with Pomegranate Peel Extracts. Annals of Agricultural Science, 59, 207-212. https://doi.org/10.1016/j.aoas.2014.11.007
Michael, M., Phebus, R.K. and Schmidt, K.A. (2010) Impact of a Plant Extract on the Viability of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus in Nonfat Yoghurt. International Dairy Journal, 20, 665-672. https://doi.org/10.1016/j.idairyj.2010.03.005
Shori, A.B. (2013) Antioxidant Activity and Viability of Lactic Acid Bacteria in Soybean-Yogurt Made from Cow and Camel Milk. Journal of Taibah University for Science, 7, 202-208. https://doi.org/10.1016/j.jtusci.2013.06.003
Gharaei-Fathabad, E. and Eslamifar, M. (2011) Isolation and Applications of One Strain of Lactobacillus paraplantarum from Tea Leaves (Camellia sinensis). American Journal of Food Technology, 6, 429-434. https://doi.org/10.3923/ajft.2011.429.434
Ali, A.A. (2011) Isolation and Identification of Lactic Acid Bacteria Isolated from Traditional Drinking Yoghurt in Khartoum State, Sudan. Current Research in Bacteriology, 4, 16-22. https://doi.org/10.3923/crb.2011.16.22
Choi, S.S., Kim, Y., Han, K.S., You, S., Oh, S. and Kim, S.H. (2006) Effects of Lactobacillus Strains on Cancer Cell Proliferation and Oxidative Stress in Vitro. Letters in Applied Microbiology, 42, 452-458. https://doi.org/10.1111/j.1472-765X.2006.01913.x
Meng, F., Liu, X.N., Jia, L., Song, Z., Deng. P. and Fan, K.M. (2010) Optimization for the Production of Exopolysaccharides from Morchella esculenta SO-02 in Submerged Culture and Its Antioxidant Activities in Vitro. Carbohydrate Polymers, 79, 700-704. https://doi.org/10.1016/j.carbpol.2009.09.032
Folkenberg, D.M., Dejmek, P., Skriver, A. and Ipsen, R. (2005) Relation between Sensory Texture Properties and Exopolysaccharide Distribution in Set and in Stirred Yoghurts Produced with Different Starter Cultures. Journal of Textural Studies, 36, 174-189. https://doi.org/10.1111/j.1745-4603.2005.00010.x
Schieber, M. and Chandel, N.S. (2014) ROS Function in Redox Signalling and Oxidative Stress. Current Biology, 24, 453-462. https://doi.org/10.1016/j.cub.2014.03.034
Commercial Yoghurt
Sayre, L.M., Perry, G. and Smith, M.A. (2008) Oxidative Stress and Neurotoxicity. Chemical Research and Toxicology, 21, 172-188. https://doi.org/10.1021/tx700210j
Mishra, V., Shah, C., Mokashe, N., Chavan, R., Yadav, H. and Prajapati, J. (2015) Probiotics as Potential Antioxidants: A Systematic Review. Journal of Agriculture and Food Chemistry, 63, 3615-3626. https://doi.org/10.1021/jf506326t
Wang, J., Zhao, X., Tian, Z., He, C.C., Yang, Y.W. and Yang, Z.N. (2015) Isolation and Characterization of Exopolysaccharide-Producing Lactobacillus plantarum SKT109 from Tibet Kefir. Polish Journal of Food and Nutritional Sciences, 65, 269-279. https://doi.org/10.1515/pjfns-2015-0023
Abdel-Hameed, E.S., Nagaty, M.A., Salman, M.S. and Bazaid, S.A. (2014) Phytochemicals, Nutritionals and Antioxidant Properties of Two Prickly Pear Cactus Cultivars (Opuntia ficus indica Mill.) Growing in Taif, KSA. Food Chemistry, 160, 31-38. https://doi.org/10.1016/j.foodchem.2014.03.060
Ishola, R.O. and Adebayo-Tayo, B.C. (2012) Screening of Lactic Acid Bacteria Isolated from Fermented Food for Bio-Molecules Production. Australian Journal of Technology, 15, 205-217.
Fawole, M.O. and Oso, B.A. (1998) Laboratory Manual of Microbiology. Spectrum Books Limited Ibadan, Owerri, 71-81.
Cheesbrough, M. (2006) District Laboratory Practice in Tropical Countries: Part 1. 2nd Edition, Cambridge University Press, Cambridge, 462. https://doi.org/10.1017/CBO9780511543470
Adebayo-Tayo, B.C. and Onilude, A.A. (2008) Screening of Lactic Acid Bacteria Strains Isolated from Some Nigerian Fermented Foods for EPS Production. World Applied Sciences Journal, 4, 741-747.
Garcia-Garibay, M. and Marshall, V.M.E. (1997) Polymer Production by Lactobacillus delbrueckii ssp. bulgaricus. Journal of Applied Bacteriology, 70, 325-328. https://doi.org/10.1111/j.1365-2672.1991.tb02943.x
Son, S. and Lewis, B.A. (2002) Free Radical Scavenging and Antioxidative Activity of Caffeic Acid Amide and Ester Analogues: Structure-Activity Relationship. Journal of Agriculture and Food Chemistry, 50, 468-472. https://doi.org/10.1021/jf010830b
Vijayalakshmi, M. and Ruckmani, K. (2016) Ferric Reducing Anti-Oxidant Power Assay in Plant Extract. Bangladesh Journal of Pharmacology, 11, 570-572. https://doi.org/10.3329/bjp.v11i3.27663
Nabavi, S.M., Ebrahimzadeh, M.A., Nabavi, S.F., Hamidinia, A. and Bekhradnia, A.R. (2008) Determination of Antioxidant Activity, Phenol and Flavonoid Content of Parrotia persica Mey. Pharmacologyonline, 2, 560-567.
Vantsawa, P.A., Maryah, U.T. and Timothy, B. (2017) Isolation and Identification of Lactic Acid Bacteria with Probiotic Potential from Fermented Cow Milk (Nono) in Unguwar Rimi Kaduna State Nigeria. American Journal of Molecular Biology, 7, 99-106. https://doi.org/10.4236/ajmb.2017.72008
Sanni, A.I., Onilude, A.A., Ogunbanwo, S.T., Fadahunsi, H.F. and Afolabi, R.O. (2002) Production of Exopolysaccharides by Lactic Acid Bacteria Isolated from Traditional Fermented Foods in Nigeria. European Food Research and Technology, 214, 405-407. https://doi.org/10.1007/s00217-002-0499-9
Savadogo, A., Ouattara, C.A.T., Savadogo, P.W., Barro, N., Ouattara, A.S. and Traore, S.A. (2004) Identification of Exopolysaccharide Producing Lactic Acid Bacteria from Burkina Faso Fermented Milk Samples. African Journal of Biotechnology, 3, 189-194.
Zhang, L., Liu, C., Li, D., Zhao, Y., Zhang, X., Zeng, X., Yang, Z. and Li, S. (2013) Antioxidant Activity of an Exopolysaccharide Isolated from Lactobacillus plantarum C88. International Journal of Biological Macromolecules, 54, 270-275. https://doi.org/10.1016/j.ijbiomac.2012.12.037
Ghalem, B.R. (2017) Antioxidant and Antimicrobial Activities of Exopolysaccharides from Yoghurt Starter. Advances in Biochemistry, 5, 97-101. https://doi.org/10.11648/j.ab.20170505.13
Xu, L., Wang, Q., Xiao, J., Liu, Q., Wang, X., Chen, T. and Zhang, Y. (2010) Characterization of Edwardsiella tarda waaL: Roles in Lipopolysaccharide Biosynthesis, Stress Adaptation, and Virulence toward Fish. Archives of Microbiology, 192, 1039-1047. https://doi.org/10.1007/s00203-010-0635-z
Li, Y., Guo, C., Yang, J., Wei, J., Xu, J. and Cheng, S. (2006) Evaluation of Antioxidant Properties of Pomegranate Peel Extract in Comparison with Pomegranate Pulp Extract. Food Chemistry, 96, 254-260. https://doi.org/10.1016/j.foodchem.2005.02.033
Qiao, D.L., Ke, C.L., Hua, B., Luo, J.G., Ye, H., Sun, Y., Yan, X.Y. and Zeng, X.X. (2009) Antioxidant Activities of Polysaccharides from Hyriopsis cumingii. Carbohydrates and Polymolecules, 78, 199-204. https://doi.org/10.1016/j.carbpol.2009.03.018
Adebayo-Tayo, B., Ishola, R. and Oyewunmi, T. (2018) Characterization, Antioxidant and Immunomodulatory Potential on Exopolysaccharide Produced by Wild Type and Mutant Weissella confusa Strains. Biotechnology Reports, 19, e00271. https://doi.org/10.1016/j.btre.2018.e00271
Adedapo, A.A., Jimoh, F.O., Koduru, S., Afolayan, A.J. and Masika, P.J. (2008) Antibacterial and Antioxidant Properties of the Methanol Extracts of the Leaves and Stems of Calpurnia aurea. BMC Complement and Alternative Medicine, 8, Article No. 53. https://doi.org/10.1186/1472-6882-8-53