U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights

Molecular Probes Developed for Mercury Methylating Genes
Published: July 15, 2016
Posted: November 07, 2016

New molecular tool probes for genes linked to toxic methylmercury. [Image courtesy Oak Ridge National Laboratory]

The new tools will enable researchers to more quickly detect and quantify microbes with these genes in the environment.

The Science
Researchers have developed deoxyribonucleic acid (DNA) and messenger ribonucleic acid (mRNA) probes to not only identify microbes that carry the genes for mercury (Hg) methylation, but also to quantify the extent to which specific types of microbes contribute to the methylation process.

The Impact
The neurotoxin methylmercury (MeHg) poses a serious risk to human health. MeHg production in nature is associated with anaerobic microbes. The development of DNA and mRNA probes represents a substantial improvement over previous work to develop both qualitative and quantitative primers for Hg-methylating genes. These new primers take into consideration the different degrees of methylation potential for specific types of microbes, which ranges from ~10% in the Archaea to ~90% in some Deltaproteobacterial species. These findings will enable a more realistic understanding of possible MeHg generation levels that may occur in a given environment, with the resulting data enabling more accurate risk management assessments.

Two genes, hgcA and hgcB, are essential for microbial Hg methylation. Detecting and estimating their abundance in microbes in conjunction with quantifying Hg species and other geochemical factors is critical in determining potential hotspots of MeHg generation in at-risk environments. Scientists at Oak Ridge National Laboratory led a team that identified a broad range of degenerate polymerase chain reaction (PCR) primers spanning known hgcAB genes to determine the presence of both genes in diverse environments. These broad-range primers were tested against an extensive set of pure cultures with published genomes that are known to methylate mercury, including 13 Deltaproteobacteria, nine Firmicutes, and nine methanogenic Archaea. For all these types of microbes, the primers not only consistently identified the methylating genes, but they enabled the team to quantify the extent to which each type of microbe methylates Hg. Environmental samples were further used to validate the primers and determine corrective calculations for DNA extraction and PCR amplification efficiencies. Taken together, these findings will enable a more realistic picture of possible MeHg generation levels that may occur in a given environment.

Contact (BER PM)
Paul Bayer
DOE Office of Biological and Environmental Research
Paul.Bayer@science.doe.gov (301-903-5324)

(PI Contact)
Dwayne Elias
Oak Ridge National Laboratory
eliasda@ornl.gov (865-574-0956)

This research was funded by the Office of Biological and Environmental Research within the U.S. Department of Energy’s Office of Science, as part of the Mercury Science Focus Area project at Oak Ridge National Laboratory.

G. A. Christensen, A. M. Wymore, A. J. King, M. Podar, R. A. Hurt Jr., E. U. Santillan, A. Soren, C. C. Brandt, S. D. Brown, A. V. Palumbo, J. D. Wall, C. C. Gilmour, and D. A. Elias, “Development and validation of broad-range qualitative and clade-specific quantitative molecular probes for assessing mercury methylation in the environment.” Applied and Environmental Microbiology (2016). DOI:10.1128/ AEM.01271-16. (Reference link)

Topic Areas:

  • Research Area: Subsurface Biogeochemical Research
  • Research Area: Genomic Analysis and Systems Biology
  • Research Area: Microbes and Communities

Division: SC-23.1 Climate and Environmental Sciences Division, BER


BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

May 10, 2019
Quantifying Decision Uncertainty in Water Management via a Coupled Agent-Based Model
Considering risk perception can improve the representation of human decision-making processes in age [more...]

May 09, 2019
Projecting Global Urban Area Growth Through 2100 Based on Historical Time Series Data and Future Scenarios
Study provides country-specific urban area growth models and the first dataset on country-level urba [more...]

May 05, 2019
Calibrating Building Energy Demand Models to Refine Long-Term Energy Planning
A new, flexible calibration approach improved model accuracy in capturing year-to-year changes in bu [more...]

May 03, 2019
Calibration and Uncertainty Analysis of Demeter for Better Downscaling of Global Land Use and Land Cover Projections
Researchers improved the Demeter model’s performance by calibrating key parameters and establi [more...]

Apr 22, 2019
Representation of U.S. Warm Temperature Extremes in Global Climate Model Ensembles
Representation of warm temperature events varies considerably among global climate models, which has [more...]

List all highlights (possible long download time)