Browsing by Author "Nugara, R.N."

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    Assessing the antioxidative potential of lactic acid bacteria inhabiting tender coconut water
    (Faculty of Graduate Studies - University of Kelaniya, Sri Lanka, 2023) Pavalakumar, D.; Undugoda, L.J.S.; Manage, P.M.; Nugara, R.N.; Kannangara, S.
    Probiotics are renowned for their beneficial impact on human health, including their antioxidative properties. Lactic acid bacteria (LAB), which constitute a major group within probiotics, have been recognized for their ability to act as potent antioxidants, providing relief from oxidative stress in the host. This study aims to evaluate the antioxidative activity of probiotic LAB inhabiting the tender coconut water samples collected from different regions of Sri Lanka. In a previous study, analysis of the collected tender coconut samples resulted in the identification of four potential probiotic strains at the species level: Lactiplantibacillus plantarum CWJ3, Lacticaseibacillus rhamnosus CWKu12, Lacticaseibacillus paracasei CWKu14, and Lacticaseibacillus casei CWM15. The antioxidative activities of these strains were evaluated using four different chemical antioxidant assays: the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay at 517 nm, the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay at 734 nm, the ferric reducing antioxidant power (FRAP) assay at 593 nm, and the total phenolic content (TPC) assay at 765 nm through spectrophotometric method. Three different concentrations of each bacterial strain (107, 108, and 109 CFU mL-1) were prepared using overnight grown cultures in deMan, Rogosa, and Sharpe broth at 37 °C, included in the study. The results indicate a significant increase (p < 0.05) in antioxidative activity for all four strains across all analyzed methods with an increase in cell concentration. Lactiplantibacillus plantarum CWJ3 exhibited the highest antioxidative potential at 109 CFU mL-1, with 88.85±0.84% radical scavenging activity in the DPPH assay, 84.0±0.14% radical scavenging activity in the ABTS assay, 0.029±0.004 mg mL-1 ascorbic acid equivalent in the FRAP assay, and 0.0052±0.0006 mg mL-1 gallic acid equivalent in the TPC assay. Conversely, Lacticaseibacillus paracasei CWKu14 demonstrated the lowest values for all antioxidative activities. Continued research on the antioxidative properties of probiotic LAB derived from tender coconut water holds promising prospects for the development of functional beverages.
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    Unveiling the Probiotic Properties of Lactic Acid Bacteria Inhabiting Tender Coconut Water
    (, Centre for Research and Knowledge Dissemination (CRKD) of the Sabaragamuwa University of Sri Lanka, 2023) Pavalakumar, D.; Undugoda, L.J.S.; Manage, P.M.; Nugara, R.N.; Kannangara, S.
    This research delves into the unexplored potential of tender coconut water as a rich source of probiotics, with a focus on identifying promising probiotic lactic acid bacteria (LAB). By employing biochemical screening techniques, four potential LAB strains were isolated: Lactiplantibacillus plantarum CWJ3, Lacticaseibacillus paracasei CWKu14, Lacticaseibacillus rhamnosus CWKu12, and Lacticaseibacillus casei CWM15. These strains were comprehensively assessed to evaluate their resilience under various conditions: pH (2, 3, and 6.5), bile (0.3% and 0.5%), phenol (0.4% and 0.6%), salt (3% and 6%) concentrations, and temperatures (20°C, 37°C, 45°C, and 60°C). Further, resistance to lysozyme (100 mg L-1), artificial saliva juice (0.3% α-amylase, at pH 6.9), simulated gastric juice (0.3% pepsin, at pH 2), and simulated intestinal juice (0.3% Ox-gall and 0.1% pancreatin at pH 7) were determined. Their antibiotic susceptibility was tested against ten antibiotics at 100 ppm, and cell surface hydrophobicity, auto-aggregation, co-aggregation with selected pathogens, antibacterial activity, hemolytic activity, and DNase activity, also were evaluated. The statistical analysis demonstrated the survival of all four strains even in demanding circumstances, with Lactiplantibacillus plantarum CWJ3 displaying the greatest resilience. Optimum growth occurred at 37°C, while none of the strains survived at 60°C. A pH of 6.5 was optimal for their growth, and Lactiplantibacillus plantarum CWJ3 stood out as the only strain capable of withstanding pH 2 after 2 hours. Lacticaseibacillus rhamnosus CWKu12 and Lacticaseibacillus casei CWM15 showed the highest percentage of auto-aggregation and co-aggregation while Lacticaseibacillus rhamnosus CWKu12 and Lactiplantibacillus plantarum CWJ3 exhibited high cell surface hydrophobicity. The strains displayed susceptibility to Clarithromycin, Erythromycin, and Azithromycin, but resistance to Cefuroxime and Streptomycin antibiotics. All four strains inhibited various food-borne pathogens, showcasing their potential as probiotics. Moreover, they displayed no hemolytic or DNase activity. Remarkably, Lactiplantibacillus plantarum CWJ3 excelled in challenging environments, making it a noteworthy contender for a probiotic role.