Abstract
The cell surface adsorption and intracellular uptake of mercuric mercury Hg(II) and methylmercury (MeHg) are important in determining the fate and transformation of Hg in the environment. However, current information is limited about their interactions with two important groups of microorganisms, i.e., methanotrophs and Hg(II)-methylating bacteria, in aquatic systems. This study investigated the adsorption and uptake dynamics of Hg(II) and MeHg by three strains of methanotrophs, Methylomonas sp. strain EFPC3, Methylosinus trichosporium OB3b, and Methylococcus capsulatus Bath, and two Hg(II)-methylating bacteria, Pseudodesulfovibrio mercurii ND132 and Geobacter sulfurreducens PCA. Distinctive behaviors of these microorganisms towards Hg(II) and MeHg adsorption and intracellular uptake were observed. The methanotrophs took up 55−80% of inorganic Hg(II) inside cells after 24 h incubation, lower than methylating bacteria (>90%). Approximately 80–95% of MeHg was rapidly taken up by all the tested methanotrophs within 24 h. In contrast, after the same time, G. sulfurreducens PCA adsorbed 70% but took up <20% of MeHg, while P. mercurii ND132 adsorbed <20% but took up negligible amounts of MeHg. These results suggest that microbial surface adsorption and intracellular uptake of Hg(II) and MeHg depend on the specific types of microbes and appear to be related to microbial physiology that requires further detailed investigation. Despite being incapable of methylating Hg(II), methanotrophs play important roles in immobilizing both Hg(II) and MeHg, potentially influencing their bioavailability and trophic transfer. Therefore, methanotrophs are not only important sinks for methane but also for Hg(II) and MeHg and can influence the global cycling of C and Hg.
| Original language | English |
|---|---|
| Article number | 121790 |
| Journal | Environmental Pollution |
| Volume | 331 |
| DOIs | |
| State | Published - Aug 15 2023 |
Funding
We thank Xiangping Yin for technical support in MeHg analyses. This research was sponsored by the Office of Biological and Environmental Research within the Office of Science of the U.S. Department of Energy (DOE), as part of the Mercury Science Focus Area project at the Oak Ridge National Laboratory (ORNL). The Hg isotopes used in this research were supplied by DOE Office of Science the Isotope Program in the Office of Nuclear Physics. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). ORNL is managed by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with DOE. LZ acknowledges support from the start-up fund from the Department of Chemistry and Environmental Science at the New Jersey Institute of Technology (NJIT), U.S. We thank Xiangping Yin for technical support in MeHg analyses. This research was sponsored by the Office of Biological and Environmental Research within the Office of Science of the U.S. Department of Energy (DOE), as part of the Mercury Science Focus Area project at the Oak Ridge National Laboratory (ORNL). The Hg isotopes used in this research were supplied by DOE Office of Science the Isotope Program in the Office of Nuclear Physics. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). ORNL is managed by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with DOE. LZ acknowledges support from the start-up fund from the Department of Chemistry and Environmental Science at the New Jersey Institute of Technology ( NJIT ), U.S..
Keywords
- Bioavailability
- Mercury
- Methanotrophs
- Microbial uptake
- Species distribution