Evidences of non-reactive mercury-selenium compounds generated from cultures of Pseudomonas fluorescens |
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Authors: | Yang Dan-Yi Chen Yu-Wei Belzile Nelson |
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Affiliation: | a Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada P3E 2C6b Department of Biology, Laurentian University, Sudbury, Ontario, Canada P3E 2C6c Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, Ontario, Canada P3E 2C6 |
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Abstract: | This work was designed to determine chemically inert mercury-selenium (Hg-Se) compounds formed in a culture of Pseudomonas fluorescens exposed to Hg2+ and SeIV (selenite). To isolate these compounds, different digestion methods were studied and sodium dodecyl sulfate (SDS) lysis was selected. The Hg0 and non-reactive Hg were determined in two series of cultures containing 0.0-6.00 μg L−1 SeIV (0.0-76.0 μmol L−1) in combination with low 5.00 μg L−1 (0.025 μmol L−1) or high 100 μg L−1 (0.500 μmol L−1) Hg2+. It was found that Hg0 formed in the culture decreased with the increase of initial SeIV, while the non-reactive Hg increased with the SeIV. In cultures with low initial Hg2+], a median SeIV (2.0 μg L−1 or 25.3 μmol L−1) resulted in about 70% of the added Hg2+ sequestered as non-reactive Hg, and in culture with high initial Hg2+, about 40% was sequestered. P. fluorescens was proved to be indispensible for the formation of the non-reactive Hg-Se compounds. The Hg:Se molar ratio in the non-reactive Hg-Se compounds was close to 1, suggesting the existence of mercuric selenide in cells. Mechanisms for the formation of the non-reactive Hg-Se compounds are proposed. |
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Keywords: | Mercury Selenium Detoxification P fluorescens Non-reactive Hg-Se compounds |
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