Browsing by Author "Undugoda, L.J.S."

Now showing 1 - 8 of 8

Analysis of naphthalene and phenanthrene degradation catabolic genes of phyllosphere bacterial strains, Alcaligenes faecalis and Alcaligenes sp. DN25
(2015) Kannangara, B.T.S.D.P.; Undugoda, L.J.S.; Sirisena, D.M.
The bacterial strains, Alcaligenes feacalis and Alcaligenes sp. DN25 which were isolated from the phyllosphere of four ornamental plant species, Ixora chinensis, Ervatamia divaricata, Hibiscus rosa-sinensis and Amaranthus cruentus in five highly polluted sites in Sri Lanka, showed the highest phenanthrene and naphthalene degradation ability. Transformation and plasmid curing results of them revealed, naphthalene and phenanthrene degradation ability of these bacterial strains were plasmid encoded character. The occurrence of naphthalene specific (nahR and nahU) genes and phenanthrene specific (phnAc and phnG) genes of these catabolic plasmids were analyzed by PCR using degenerate primers. According to the amplification results, plasmids of Alcaligenes faecalis and Alcaligenes sp. DN25 harbour nahR, nahU and phnG genes but, lack of phnAc gene. RFLP and sequence data of nahU and nahR amplicons revealed, both of these genes were homologous to these two bacterial strains. But, phnG gene of two phenanthrene and naphthalene degrading phyllosphere bacterial strains was coexistence as two distinct copies of alleles.
Aromatic hydrocarbon degrading Phyllosphere Fungi
(University of Sri Jayawardhanapura, 2013) Undugoda, L.J.S.; Kannangara, S.; Sirisena, D.M.
Aromatic hydrocarbon degrading phyllosphere microorganisms
(University of Kelaniya, 2013) Undugoda, L.J.S.; Kannangara, S.; Sirisena, D.M.
Pyrogenic nature of the most recalcitrant aromatic hydrocarbons elevates their persistency in the environment and rapid bioaccumulation in living organisms. Therefore, air pollution by aromatic hydrocarbons is one of the current concerns. It has been shown that utilization of phyllosphere microorganisms as bioremediators is an efficient means of remediating these air pollutants. This study was carried out to isolate aromatic hydrocarbon degrading phyllosphere fungi and bacteria from selected plants; Ixora sp., Hibiscus sp., Ervatamia sp., and Amaranth sp., which are highly abundant in roadsides around the oil refinery at Sapugaskanda and high traffic areas. Phenanthrene, naphthalene, xylene and toluene degradation ability of the isolated bacteria and fungi was then examined using plate assays and spectrophotometric analysis. The best degraders were selected for further identification and characterization. Phenanthrene, naphthalene, toluene and xylene utilization rates of identified phyllosphere fungi; Penicillium sp. Aspergillus sp. and Trichoderma sp. were comparatively higher than that of isolated phyllosphere bacterial species; Pseudomonas sp., Paracoccus sp., Klebsiella sp. and Alcaligenes sp. Penicillium janthinellum utilized more than 90% of polyaromatic hydrocarbons in the medium during seven days’ incubation, but Pseudomonas sp. required 14 days of incubation to achieve that level. Moreover, the best toluene degrader Aspergillus niger degraded toluene very efficiently compared to Pseudomonas sp. The best xylene degrader Aspergilus flavus utilized only 57.35% of xylene in the medium in seven days, but 90% degradation was observed in 14 days. Therefore, xylene degradation ability of fungi was comparatively less but significantly higher than that of bacteria. Bioremediation is a very economically and environmentally friendly strategy used in cleaning of AH contaminated sites. According to the results, Penicillium spp. and Aspergillus spp. could be considered as the best fungal candidates for bioremediation. Pseudomonas sp. was able to degrade all tested AHs at relatively high efficiencies. Therefore, it can be considered as a general AH degrader. Therefore, ability of these microorganisms to degrade AH while surviving under environmental stress makes them very suitable candidates for bioremediation.
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.
Characterization and biological prospecting of phyllosphere microorganisms capable in aromatic hydrocarbon degradation
(2016) Undugoda, L.J.S.
Isolation of aromatic hydrocarbon degrading phyllosphere bacteria
(Sri Lanka Association for the Advancement of Science, 2013) Undugoda, L.J.S.; Kannangara, S.; Sirisena, D.M.
Moss endophytes and polyaromatic hydrocarbon degradation
(Sri Lanka Association for the Advancement of Science, 2015) Ambadeniya, A.R.P.D.U.K.R.; Undugoda, L.J.S.; Kannangara, B.T.S.D.P.
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.