Browsing by Author "Aththanayake, A. M. K. C. B."

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Comparison of the tolerance of cadmium (Cd2+), lead (Pb2+) and their mixtures by Staphylococcus sp. isolated from a water body receiving textile effluent
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Aththanayake, A. M. K. C. B.; Rathnayake, I. V. N.; Deeyamulla, M. P.
Cd2+ and Pb2+ are widely used heavy metals in industries such as electroplating, battery, plastic and pigment production etc. These heavy metals are considered as highly threatening substances to human body, which can cause carcinogenic effects and organ dysfunctions. The isolated Staphylococcus sp. from waste effluent was exposed to a range of single and mixed metal concentrations of Cd2+ and Pb2+ in modified Tris-minimal medium. The growth patterns of Staphylococcus sp. during 24-hour intervals were monitored spectrophotometrically at 600 nm. The effective concentrations (EC50) of Staphylococcus sp. were calculated up to 72 hours. Staphylococcus sp. showed a gradually increasing growth in Pb2+ containing medium, where as a decreasing growth in Cd2+ containing medium was observed after 48 hours. It showed an increasing growth when grown in the presence of both metals. EC50 values at 24, 48 and 72 hours with Cd2+ and their mixture showed a gradual decrease while EC50 values of Pb2+ showed a gradual increase. Results of the study indicated that Staphylococcus sp. has comparatively high tolerance to Pb2+ than Cd2+ and their mixtures
Potential use of Chlorella vulgaris KCBAL01 from a freshwater stream receiving treated textile effluent in hexavalent chromium [Cr(VI)] removal in extremely acidic conditions
(Journal of Environmental Science and Health, 2022) Aththanayake, A. M. K. C. B.; Rathnayake, I. V. N.; Deeyamullab, M. P.; Megharaj, Mallavarapu
Remediation of hexavalent chromium with conventional chemical and physical methods is a costly process, while replacing some critical steps in physiochemical remediation with self-sustaining bioremediation agents are expected to be cost-effective and environmentally friendly implementation. In this study, a microalga isolated from a freshwater stream receiving treated textile wastewater was identified up to its molecular level and investigated its ability to tolerate and remove hexavalent chromium from extremely acidic conditions under different temperatures. The ability of microalgae to tolerate and remove Cr(VI) was investigated by growing it in BG11 media with different pH (1, 2, 3 & 7), amended with several concentrations of Cr(VI) and incubated under different temperatures for 96 hrs. Microalga was identified as Chlorella vulgaris and found that the isolated strain has a higher hexavalent chromium removal potential in extremely acidic conditions than in neutral pH conditions at 25 C. In contrast, its Cr(VI) removal potential is significantly influenced by the pH and temperature of the growth medium. Furthermore, it exhibited a permanent viability loss at extreme acidic conditions (pH 1 3) and prolonged exposure to the higher chromium content. The microalga investigated will be a highly useful bioagent in hexavalent chromium remediation in high acidic conditions.
Staphylococcus edaphicus KCB02A11 incorporated with natural adsorbents: first report on its tolerance and removal of hexavalent chromium [Cr(VI)]
(Springer Link, 2024) Aththanayake, A. M. K. C. B.; Rathnayake., I. V. N.; Deeyamulla, M. P.; Megharaj, Mallavarapu
Deteriorating the quality of different parts of the ecosystem due to toxic metals is a serious global issue. Hexavalent chromium is a metal that can cause adverse effects on all living beings, including plants, animals, and microorganisms, on exposure to high concentrations for prolonged periods. Removing hexavalent chromium from various types of wastes is challenging; hence the present study investigated the use of bacteria incorporated with selected natural substrates in removing hexavalent chromium from water. Isolated Staphylococcus edaphicus KCB02A11 has shown higher removal efficiency with a wide hexavalent chromium range (0.025-8.5 mg/L) within 96 h. Incorporating the isolated strain with natural substrates commonly found in the environment (hay and wood husk) showed high removal potential [100% removal with 8.5 mg/L of Cr(VI)], even within less than 72 h, with the formation of biofilms on the used substrates applied for metal removal on a large scale for prolonged periods. This study is the first report investigating hexavalent chromium tolerance and removal by Staphylococcus edaphicus KCB02A11.
Staphylococcus edaphicus KCB02A11 incorporated with natural adsorbents: first report on its tolerance and removal of hexavalent chromium [Cr(VI)]
(2023) Aththanayake, A. M. K. C. B.; Rathnayake, I. V. N.; Deeyamulla, M. P.; Megharaj, Mallavarapu
Deteriorating the quality of different parts of the ecosystem due to toxic metals is a serious global issue. Hexavalent chromium is a metal that can cause adverse effects on all living beings, including plants, animals, and microorganisms, on exposure to high concentrations for prolonged periods. Removing hexavalent chromium from various types of wastes is challenging; hence the present study investigated the use of bacteria incorporated with selected natural substrates in removing hexavalent chromium from water. Isolated Staphylococcus edaphicus KCB02A11 has shown higher removal efficiency with a wide hexavalent chromium range (0.025-8.5 mg/L) within 96 h. Incorporating the isolated strain with natural substrates commonly found in the environment (hay and wood husk) showed high removal potential [100% removal with 8.5 mg/L of Cr(VI)], even within less than 72 h, with the formation of biofilms on the used substrates applied for metal removal on a large scale for prolonged periods. This study is the first report investigating hexavalent chromium tolerance and removal by Staphylococcus edaphicus KCB02A11.