Nanomolar Copper Enhances Mercury Methylation by Desulfovibrio desulfuricans ND132

Lu, Xia; Johs, Alexander; Zhao, Linduo; Wang, Lihong; Pierce, Eric M.; Gu, Baohua

doi:10.1021/acs.estlett.8b00232

Title: Nanomolar Copper Enhances Mercury Methylation by Desulfovibrio desulfuricans ND132

Abstract

Methylmercury (MeHg) is produced by certain anaerobic microorganisms, such as the sulfate-reducing bacterium Desulfovibrio desulfuricans ND132, but environmental factors affecting inorganic mercury [Hg(II)] uptake and methylation remain unclear. We report that the presence of a small amount of copper ions [Cu(II), <100 nM] enhances Hg(II) uptake and methylation by washed cells of ND132, while Hg(II) methylation is inhibited at higher Cu(II) concentrations because of the toxicity of copper to the microorganism. The enhancement or inhibitory effect of Cu(II) is dependent on both time and concentration. The presence of nanomolar concentrations of Cu(II) facilitates rapid uptake of Hg(II) (within minutes) and doubles MeHg production within a 24 h period, but micromolar concentrations of Cu(II) completely inhibit Hg(II) methylation. Metal ions such as zinc [Zn(II)] and nickel [Ni(II)] also inhibit but do not enhance Hg(II) methylation under the same experimental conditions. Furthermore, these observations suggest a synergistic effect of Cu(II) on Hg(II) uptake and methylation, possibly facilitated by copper transporters or metallochaperones in this organism, and highlight the fact that complex environmental factors affect MeHg production in the environment.

Authors:

^[1];

^[2];

^[2]; Wang, Lihong ^[2];

^[2];

^[3]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lanzhou Univ., Lanzhou (China)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)

Publication Date:: Tue May 29 00:00:00 EDT 2018

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:: 1456798

Grant/Contract Number:: AC05-00OR22725

Resource Type:: Accepted Manuscript

Journal Name:: Environmental Science & Technology Letters (Online)

Additional Journal Information:: Journal Name: Environmental Science & Technology Letters (Online); Journal Volume: 5; Journal Issue: 6; Journal ID: ISSN 2328-8930

Publisher:: American Chemical Society (ACS)

Country of Publication:: United States

Language:: English

Subject:: 59 BASIC BIOLOGICAL SCIENCES

Citation Formats


                    Lu, Xia, Johs, Alexander, Zhao, Linduo, Wang, Lihong, Pierce, Eric M., and Gu, Baohua. Nanomolar Copper Enhances Mercury Methylation by Desulfovibrio desulfuricans ND132.  United States: N. p., 2018. 
Web.  doi:10.1021/acs.estlett.8b00232.

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                    Lu, Xia, Johs, Alexander, Zhao, Linduo, Wang, Lihong, Pierce, Eric M., & Gu, Baohua. Nanomolar Copper Enhances Mercury Methylation by Desulfovibrio desulfuricans ND132.  United States.  https://doi.org/10.1021/acs.estlett.8b00232

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                    Lu, Xia, Johs, Alexander, Zhao, Linduo, Wang, Lihong, Pierce, Eric M., and Gu, Baohua. Tue .  
"Nanomolar Copper Enhances Mercury Methylation by Desulfovibrio desulfuricans ND132".  United States.  https://doi.org/10.1021/acs.estlett.8b00232.  https://www.osti.gov/servlets/purl/1456798.

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@article{osti_1456798,

  title        = {Nanomolar Copper Enhances Mercury Methylation by Desulfovibrio desulfuricans ND132},

  author       = {Lu, Xia and Johs, Alexander and Zhao, Linduo and Wang, Lihong and Pierce, Eric M. and Gu, Baohua},

  abstractNote = {Methylmercury (MeHg) is produced by certain anaerobic microorganisms, such as the sulfate-reducing bacterium Desulfovibrio desulfuricans ND132, but environmental factors affecting inorganic mercury [Hg(II)] uptake and methylation remain unclear. We report that the presence of a small amount of copper ions [Cu(II), <100 nM] enhances Hg(II) uptake and methylation by washed cells of ND132, while Hg(II) methylation is inhibited at higher Cu(II) concentrations because of the toxicity of copper to the microorganism. The enhancement or inhibitory effect of Cu(II) is dependent on both time and concentration. The presence of nanomolar concentrations of Cu(II) facilitates rapid uptake of Hg(II) (within minutes) and doubles MeHg production within a 24 h period, but micromolar concentrations of Cu(II) completely inhibit Hg(II) methylation. Metal ions such as zinc [Zn(II)] and nickel [Ni(II)] also inhibit but do not enhance Hg(II) methylation under the same experimental conditions. Furthermore, these observations suggest a synergistic effect of Cu(II) on Hg(II) uptake and methylation, possibly facilitated by copper transporters or metallochaperones in this organism, and highlight the fact that complex environmental factors affect MeHg production in the environment.},

  doi          = {10.1021/acs.estlett.8b00232},

  journal      = {Environmental Science & Technology Letters (Online)},

  number       = 6,

  volume       = 5,

  place        = {United States},

  year         = {Tue May 29 00:00:00 EDT 2018},

  month        = {Tue May 29 00:00:00 EDT 2018}

}

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https://doi.org/10.1021/acs.estlett.8b00232

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Figure 1: Methylmercury (MeHg) production by washed cells of D. desulfuricans ND132 at 2 and 24 h in the presence of various divalent metal ions: (a) 50 nM and (b) 50 $μ$M each. The initial concentration of added Hg(Ⅱ) (as HgCl₂) was 25 nM, which was mixed first with themore »

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