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The efficiencies of inorganic mercury bio-methylation by aerobic bacteria under different oxygen concentrations.
- Source :
-
Ecotoxicology and environmental safety [Ecotoxicol Environ Saf] 2021 Jan 01; Vol. 207, pp. 111538. Date of Electronic Publication: 2020 Nov 04. - Publication Year :
- 2021
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Abstract
- Limited information is available about the bio-methylation of inorganic mercury (iHg) under aerobic conditions. In this study, two γ-proteobacteria strains (P. fluorescens TGR-B2 and P. putida TGR-B4) were obtained from the soil of The Three Gorges Reservoir (TGR), demonstrating effective aerobic transformation capacities of iHg into methylmercury (MeHg). Based on periodical changes in soil oxygen content of the TGR, a culture system was established, in which 300 ng Hg (II) L <superscript>-1</superscript> and O <subscript>2</subscript> were set at 7%, 14%, and 21%, respectively. Results indicated that the two strains differed significantly in bacterial growth rate and MeHg production. The kinetic model of MeHg showed typical characteristics of a "two-staged" process: The first stage was dominated by bio-methylation, which was shown by increasing of net MeHg content. Moreover, the second stage was dominated by bio-demethylation, which decreased net MeHg content. Thus, we hypothesized that the mechanism of aerobic bacterial iHg bio-methylation: (1) should inefficiency compared to anaerobic bacteria i.e.SRB, which were regulated by hgcA/B gene clusters, (2) might be regarded as a passive stress response and depended on the bacterial iHg intoxication threshold and MeHg tolerance threshold.<br /> (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)
Details
- Language :
- English
- ISSN :
- 1090-2414
- Volume :
- 207
- Database :
- MEDLINE
- Journal :
- Ecotoxicology and environmental safety
- Publication Type :
- Academic Journal
- Accession number :
- 33254400
- Full Text :
- https://doi.org/10.1016/j.ecoenv.2020.111538