Mercury methylating microbial communities of boreal forest soils

Xu, Jia‐Zhuang; Buck, Moritz; Eklöf, Karin; Ahmed, Omneya; Schaefer, Jeffra K.; Bishop, Kevin; Skyllberg, Ulf; Björn, Erik; Bertilsson, Stefan; Bravo, Andrea G.

doi:10.1038/s41598-018-37383-z

Cited by 54 publications

(40 citation statements)

References 83 publications

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“…Microorganisms that live in soil can transform inorganic Hg (II) species into Hg 0 by using the enzyme Hg reductase, which is found in various bacteria, such as Pseudomonas sp., Staphylococcus aureus, Thiobacillus and many others [101]. Increases in temperature might lead to increases in biological activity as well as higher Hg 2+ methylation rates [102].…”

Section: Referencesmentioning

confidence: 99%

Mercury in the terrestrial environment: a review

2020

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Background Environmental contamination by mercury is and will continue to be a serious risk for human health. Pollution of the terrestrial environment is particularly important as it is a place of human life and food production. This publication presents a review of the literature on issues related to mercury pollution of the terrestrial environment: soil and plants and their transformations. Results Different forms of atmospheric Hg may be deposited on surfaces by way of wet and dry processes. These forms may be sequestered within terrestrial compartments or emitted back into the atmosphere, and the relative importance of these processes is dependent on the form of Hg, the surface chemistry, and the environmental conditions. On the land surface, Hg deposition mainly occurs in the oxidized form (Hg2+), and its transformations are associated primarily with the oxidation–reduction potential of the environment and the biological and chemical processes of methylation. The deposition of Hg pollutants on the ground with low vegetation is as 3–5 times lower than that in forests. The estimation of Hg emissions from soil and plants, which occur mainly in the Hg0 form, is very difficult. Generally, the largest amounts of Hg are emitted from tropical regions, followed by the temperate zone, and the lowest levels are from the polar regions. Areas with vegetation can be ranked according to the size of the emissions as follows: forests > other areas (tundra, savannas, and chaparral) > agricultural areas > grassland ecosystems; areas of land devoid of vegetation emit more Hg than those with plants. In areas with high pollution, such as areas near Hg mines, the Hg content in soil and plants is much higher than in other areas. Conclusions Mercury is recognized as a toxic, persistent, and mobile contaminant; it does not degrade in the environment and becomes mobile because of the volatility of the element and several of its compounds. Atmospheric contamination by mercury continues to be one of the most important environmental problems in the modern world. The general conclusions were drawn from a review of the literature and presented in this paper.

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Section: Referencesmentioning

confidence: 99%

Mercury in the terrestrial environment: a review

2020

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“…The production of MeHg in freshwater wetlands has been attributed to a select group of anaerobic δ‐Proteobacteria and Archaea , specifically sulfate‐reducing bacteria (SRB) (Gilmour et al ., 1992; Gilmour et al ., 1998; Yu et al ., 2010), iron‐reducing bacteria (IRB) (Fleming et al ., 2006; Yu et al ., 2012; Xu et al ., 2019), syntrophs (Bae et al ., 2014) and methanogens (Hamelin et al ., 2011; Gilmour et al ., 2018). Additional phyla (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Additional phyla (i.e. Firmicutes ) have recently been identified with the capacity to produce MeHg (Gilmour et al ., 2013; Podar et al ., 2015; Xu et al ., 2019); however, their role has yet to be explicitly demonstrated in the environment. With the recent discovery of the gene products necessary for Hg methylation, HgcAB (Parks et al ., 2013), we can now identify specific Hg methylating communities within the environment (Bae et al ., 2014; Liu et al ., 2014; Schaefer et al ., 2014; Christensen et al ., 2016; Bravo et al ., 2018) and combine this approach with incubation studies to better understand the organisms which contribute to MeHg production (Christensen et al ., 2017).…”

Section: Introductionmentioning

confidence: 99%

Anaerobic guilds responsible for mercury methylation in boreal wetlands of varied trophic status serving as either a methylmercury source or sink

Schaefer

Kronberg

Björn

et al. 2020

Environmental Microbiology

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Wetlands are common sites of active Hg methylation by anaerobic microbes; however, the amount of methylmercury produced varies greatly, as Hg methylation is dependent upon both the availability of Hg and the composition and activity of the microbial community involved. In this study, we identified the major microbial guilds responsible for Hg methylation along a trophic gradient composed of two sites and three different types of wetlands: a bog-fen peatland gradient and a black alder swamp, serving as net sources and a sink for methylmercury respectively. Ironreducing bacteria in the Geobacteraceae were important Hg methylators across all wetlands and seasons examined, as evidenced by abundant 16S rRNA and hgcA transcripts clustering with this family. Molybdate inhibited Hg methylation more efficiently in the peatlands than in the swamp, suggesting an increasing role of sulfate-reducing bacteria and/or related syntrophs in the methylation of Hg with decreasing trophic status. Sulfate addition failed to increase Hg methylation rates in the peatlands, suggesting that SRBs/ syntrophs were instead likely metabolizing alternative substrates such as syntrophic fermentation of organic compounds with methanogens. These results highlight the interconnectivity of anaerobic metabolism and importance of community dynamics on the methylation of Hg in wetlands with different trophic status.

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“…Increases in temperature might lead to increases in biological activity as well as higher Hg 2+ methylation rates [111].…”

Section: Methylmercurymentioning

confidence: 99%

Mercury in the terrestrial environment: a review

Gworek¹,

Dmuchowski²,

Baczewska-Dąbrowska

2020

Preprint

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Environmental contamination by mercury is and will continue to be a serious risk for human health. Pollution of the terrestrial environment is particularly important as it is a place of human life and food production. Publication presents a review of the literature on issues related to Hg pollution of the terrestrial environment: soil and plants and their transformations. Different forms of atmospheric Hg may be deposited on surfaces by way of wet and dry processes. These forms may be sequestered within terrestrial compartments or emitted back into the atmosphere, and the relative importance of these processes is dependent on the form of Hg, the surface chemistry, and the environmental conditions. On the land surface, Hg deposition mainly occurs in the oxidized form (Hg 2+ ), and its transformations are associated primarily with the oxidation-reduction potential of the environment and the biological and chemical processes of methylation. The deposition of Hg on ground with low vegetation as 3–5 times lower than that in forests. The estimation of Hg emissions from soil and plants, which occur mainly in the Hg 0 form, is very difficult. Generally, the largest amounts of Hg are emitted from tropical regions, and the lowest levels are from the polar regions.

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Mercury methylating microbial communities of boreal forest soils

Cited by 54 publications

References 83 publications

Mercury in the terrestrial environment: a review

Mercury in the terrestrial environment: a review

Anaerobic guilds responsible for mercury methylation in boreal wetlands of varied trophic status serving as either a methylmercury source or sink

Mercury in the terrestrial environment: a review

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