The Effects of Copper on 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 poorly understood. Copper (Cu) is a known micronutrient for microbes at relatively low concentrations but toxic at high concentrations. We report that the presence of a small amount of Cu (<100 nM) enhances Hg(II) uptake and methylation by washed cells of ND132, while Hg(II) methylation is inhibited at higher Cu concentrations due to copper toxicity. The enhancement or inhibitory effect of Cu is both time and concentration dependent: The presence of nanomolar concentrations of Cu facilitates rapid uptake of Hg(II) (within minutes) and doubles MeHg production within a 24 h period, but micromolar concentrations of Cu completely inhibit Hg(II) methylation. The enhanced Hg(II) methylation at low Cu concentrations cannot be attributed simply to increased microbial activity since cell growth and metabolism remain unchanged with or without Cu. Metal ions such as zinc (Zn) and nickel (Ni) also inhibit but do not enhance Hg(II) methylation under the same experimental conditions. These observations suggest a synergistic effect of Cu on Hg(II) uptake and methylation, possibly facilitated by copper transporters or metallochaperones in this organism, and highlight that complex environmental factors affect MeHg production in the environment.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B54B..07G
- Keywords:
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- 0409 Bioavailability: chemical speciation and complexation;
- BIOGEOSCIENCESDE: 0432 Contaminant and organic biogeochemistry;
- BIOGEOSCIENCESDE: 0454 Isotopic composition and chemistry;
- BIOGEOSCIENCESDE: 0491 Food webs and trophodynamics;
- BIOGEOSCIENCES