Microbial Transformations in the Mercury Cycle

Lin, Cheng-Ju; Yee, Nathan; Barkay, Tamar

doi:10.1002/9781118146644.ch5

Cited by 56 publications

(75 citation statements)

References 197 publications

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“…This operon varies in structure and is made up of genes that encode the functional proteins for regulation (merR) and transport (merC, merE, merF, merG, merT) of Hg 2+ to the cytoplasm where it is reduced by merA. The merB is also found downstream of merA, a periplasmic scavenging protein (merP) and an additional one or two regulatory proteins (MerR, MerD) [150]. The genetic determinant responsible for multiple HM (As, Pb, Cd, Hg, Ni, Co and Cu) resistance patterns observed in 45 Gram positive and Gram negative bacteria isolated from the rhizosphere of Alyssum murale and Ni rich soil was examined by Abou-Shanab et al [118] using polymerase chain reaction in combination with DNA sequencing.…”

Section: Bacterial Interaction With Heavy Metalsmentioning

confidence: 99%

Heavy Metal Pollution from Gold Mines: Environmental Effects and Bacterial Strategies for Resistance

Fashola

Ngole‐Jeme

Babalola

2016

IJERPH

545

225

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Mining activities can lead to the generation of large quantities of heavy metal laden wastes which are released in an uncontrolled manner, causing widespread contamination of the ecosystem. Though some heavy metals classified as essential are important for normal life physiological processes, higher concentrations above stipulated levels have deleterious effects on human health and biota. Bacteria able to withstand high concentrations of these heavy metals are found in the environment as a result of various inherent biochemical, physiological, and/or genetic mechanisms. These mechanisms can serve as potential tools for bioremediation of heavy metal polluted sites. This review focuses on the effects of heavy metal wastes generated from gold mining activities on the environment and the various mechanisms used by bacteria to counteract the effect of these heavy metals in their immediate environment.

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Section: Bacterial Interaction With Heavy Metalsmentioning

confidence: 99%

Heavy Metal Pollution from Gold Mines: Environmental Effects and Bacterial Strategies for Resistance

Fashola

Ngole‐Jeme

Babalola

2016

IJERPH

545

225

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“…Mercury methylation and demethylation are considered to be mainly microbially driven processes . The underlying mechanisms for the individual species or group of species were recently reviewed , as well as the genetic basis of the bacterial methylation . In biofilms, higher net Hg methylation potential has been demonstrated compared with that measured in sediments and the water column .…”

Section: Hg Transformation In Freshwater Biofilmsmentioning

confidence: 99%

Mercury bioavailability, transformations, and effects on freshwater biofilms

Dranguet

Faucheur

2017

Enviro Toxic and Chemistry

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Mercury (Hg) compounds represent an important risk to aquatic ecosystems because of their persistence, bioaccumulation, and biomagnification potential. In the present review, we critically examine state-of-the-art studies on the interactions of Hg compounds with freshwater biofilms, with an emphasis on Hg accumulation, transformations, and effects. Freshwater biofilms contain both primary producers (e.g., algae) and decomposers (e.g., bacteria and fungi), which contribute to both aquatic food webs and the microbial loop. Hence they play a central role in shallow water and streams, and also contribute to Hg trophic transfer through their consumption. Both inorganic and methylated mercury compounds accumulate in biofilms, which could transform them mainly by methylation, demethylation, and reduction. Accumulated Hg compounds could induce diverse metabolic and physiological perturbations in the microorganisms embedded in the biofilm matrix and affect their community composition. The bioavailability of Hg compounds, their transformations, and their effects depend on their concentrations and speciation, ambient water characteristics, biofilm matrix composition, and microorganism-specific characteristics. The basic processes governing the interactions of Hg compounds with biofilm constituents are understudied. The development of novel conceptual and methodological approaches allowing an understanding of the chemo-and biodynamic aspects is necessary to improve the knowledge on Hg cycling in shallow water as well as to enable improved use of freshwater biofilms as potential indicators of water quality and to support better informed risk assessment. Environ Toxicol Chem 2017;36:3194-3205. # 2017 SETAC

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“…Mercury methylation or reduction can lead to volatilization, but only the latter is believed to operate as a resistance mechanism, because organomercurials are highly toxic [144]. Bacterial mediated mercury methylation occurs anaerobically, is coupled to dissimilatory reduction of various electron acceptors, mostly sulfate [215], and has been extensively studied and recently reviewed [216,217]. There exists a limited understanding of mercury methylation in archaea, but it has been shown to occur in certain methanogens [218].…”

Section: Mercurymentioning

confidence: 99%

The Confluence of Heavy Metal Biooxidation and Heavy Metal Resistance: Implications for Bioleaching by Extreme Thermoacidophiles

et al. 2015

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Extreme thermoacidophiles (Topt > 65 °C, pHopt < 3.5) inhabit unique environments fraught with challenges, including extremely high temperatures, low pH, as well as high levels of soluble metal species. In fact, certain members of this group thrive by metabolizing heavy metals, creating a dynamic equilibrium between biooxidation to meet bioenergetic needs and mechanisms for tolerating and resisting the toxic effects of solubilized metals. Extremely thermoacidophilic archaea dominate bioleaching operations at elevated temperatures and have been considered for processing certain mineral types (e.g., chalcopyrite), some of which are recalcitrant to their mesophilic counterparts. A key issue to consider, in addition to temperature and pH, is the extent to which solid phase heavy metals are solubilized and the concomitant impact of these mobilized metals on the microorganism's growth physiology. Here, extreme thermoacidophiles are examined from the perspectives of biodiversity, heavy metal biooxidation, metal resistance mechanisms, microbe-solid interactions, and application of these archaea in biomining operations.

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Microbial Transformations in the Mercury Cycle

Cited by 56 publications

References 197 publications

Heavy Metal Pollution from Gold Mines: Environmental Effects and Bacterial Strategies for Resistance

Heavy Metal Pollution from Gold Mines: Environmental Effects and Bacterial Strategies for Resistance

Mercury bioavailability, transformations, and effects on freshwater biofilms

The Confluence of Heavy Metal Biooxidation and Heavy Metal Resistance: Implications for Bioleaching by Extreme Thermoacidophiles

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