Mercury Methylation Independent of the Acetyl-Coenzyme A Pathway in Sulfate-Reducing Bacteria

Ekstrom, Eileen B.; Morel, François M. M.; Benoit, Janina M.

doi:10.1128/aem.69.9.5414-5422.2003

Cited by 126 publications

(112 citation statements)

References 54 publications

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“…The methylation process has long been known to occur in sub-oxic environments, like sediments or stagnant basins, where inorganic Hg is converted into MeHg by sulfate-reducing bacteria metabolising organic matter. [95,96] There are other interactions between the organic carbon and Hg cycles that are not as well understood. For example, DOM may provide stabilising ligands to maintain Hg in dissolved form, [97] and C-DOM absorbs UV radiation and thus provides an important control on photo-reduction and other photo-initiated processes in surface water.…”

Section: Microbial Carbon Processing and Mercury In The Arcticmentioning

confidence: 99%

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

124

147

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Environmental context. Mercury, in its methylated form, is a neurotoxin that biomagnifies in marine and terrestrial foodwebs leading to elevated levels in fish and fish-eating mammals worldwide, including at numerous Arctic locations. Elevated mercury concentrations in Arctic country foods present a significant exposure risk to Arctic people. We present a detailed review of the fate of mercury in Arctic terrestrial and marine ecosystems, taking into account the extreme seasonality of Arctic ecosystems and the unique processes associated with sea ice and Arctic hydrology.Abstract. This review is the result of a series of multidisciplinary meetings organised by the Arctic Monitoring and Assessment Programme as part of their 2011 Assessment 'Mercury in the Arctic'. This paper presents the state-of-the-art knowledge on the environmental fate of mercury following its entry into the Arctic by oceanic, atmospheric and terrestrial pathways. Our focus is on the movement, transformation and bioaccumulation of Hg in aquatic (marine and fresh water) and terrestrial ecosystems. The processes most relevant to biological Hg uptake and the potential risk associated with Hg exposure in wildlife are emphasised. We present discussions of the chemical transformations of newly deposited or transported Hg in marine, fresh water and terrestrial environments and of the movement of Hg from air, soil and water environmental compartments into food webs. Methylation, a key process controlling the fate of Hg in most ecosystems, and the role of trophic processes in controlling Hg in higher order animals are also included. Case studies on Eastern Beaufort Sea beluga (Delphinapterus leucas) and landlocked Arctic char (Salvelinus alpinus) are presented as examples of the relationship between ecosystem trophic processes and biologic Hg levels. We examine whether atmospheric mercury depletion events (AMDEs) contribute to increased Hg levels in Arctic biota and provide information on the links between organic carbon and Hg speciation, dynamics and bioavailability. Long-term sequestration of Hg into non-biological archives is also addressed. The review concludes by identifying major knowledge gaps in our understanding, including:(1) the rates of Hg entry into marine and terrestrial ecosystems and the rates of inorganic and MeHg uptake by Arctic microbial and algal communities; (2) the bioavailable fraction of AMDE-related Hg and its rate of accumulation by biota and (3) the fresh water and marine MeHg cycle in the Arctic, especially the marine MeHg cycle.

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Section: Microbial Carbon Processing and Mercury In The Arcticmentioning

confidence: 99%

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

124

147

View full text Add to dashboard Cite

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“…Since the study on SRM pure-culture strains Desulfovibrio deseulfuricans first demonstrating its capacity for Hg methylation (Choi et al 1994), many studies linking Hg methylation to SRM species were conducted in natural habitats (Compeau and Bartha 1985;King et al 2000;Benoit et at. 2001;Ekstrom et al 2003). Recently, it was suggested that only SRM belonging to the Deltaproteobacteria group can methylate Hg (Ranchou-Peyruse et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Linkage between community diversity of sulfate-reducing microorganisms and methylmercury concentration in paddy soil

Liu

Zheng

Zhang

et al. 2013

Environ Sci Pollut Res

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Sulfate-reducing microorganisms (SRM) have been thought to play a key role in mercury (Hg) methylation in anoxic environments. The current study examined the linkage between SRM abundance and diversity and contents of methylmercury (MeHg) in paddy soils collected from a historical Hg mining area in China. Soil profile samples were collected from four sites over a distance gradient downstream the Hg mining operation. Results showed that MeHg content in the soil of each site significantly decreased with the extending distance away from Hg mine. Soil MeHg content was correlated positively with abundance of SRM and the contents of organic matter (OM), NH 4 + , SO 4 2− , and Hg. The abundances of SRM based on dissimilatory (bi) sulfite reductase (dsrAB) gene at 0-40 cm depths were higher than those at 40-80 cm depth at all sites. The SRM community composition varied in the soils of different sampling sites following terminal restriction fragment length polymorphism (T-RFLP) and phylogenetic analyses, which appeared to be correlated with contents of MeHg, OM, NH 4 + , and SO 4 2− through canonical correspondence analysis. The dominant groups of SRM in the soils examined belonged to Deltaproteobacteria and some unknown SRM clusters that could have potential for Hg methylation. These results advance our understanding of the relationship between SRM and methylmercury concentration in paddy soil.

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“…We recently determined the genome sequence for D. desulfuricans ND132 (3) and described its physiological characteristics (17). Desulfovibrio africanus produces MeHg (14) and has different morphotypes associated with a cell cycle (8)(9)(10)18). Its genome sequence was determined and is summarized here to facilitate future analyses into SRBs, mercury methylation, and cell cycle differentiation and regulation.…”

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confidence: 99%