Nav: Home

Newly identified microbial process could reduce toxic methylmercury levels

May 31, 2017

OAK RIDGE, Tenn. May 31, 2017 - A team led by the Department of Energy's Oak Ridge National Laboratory has identified a novel microbial process that can break down toxic methylmercury in the environment, a fundamental scientific discovery that could potentially reduce mercury toxicity levels and support health and risk assessments.

Methylmercury is a neurotoxin that forms in nature when mercury interacts with certain microbes living in soil and waterways. It accumulates at varying levels in all fish--particularly large predatory fish such as tuna and swordfish--and, when consumed in large quantities, can potentially cause neurological damage and developmental disorders, especially in children.

A previous ORNL-led study, published in Science in 2013, unlocked the genetic code that led scientists to accurately identify microbes responsible for methylmercury production in the environment. Following this finding, the ORNL team has now discovered which bacteria perform the reverse process, called demethylation. Details are published in Science Advances.

"Much attention has focused on mercury methylation or how methylmercury forms, but few studies to date have examined microbial demethylation, or the breakdown of methylmercury at environmentally relevant conditions," said Baohua Gu, co-author and a team lead in ORNL's Mercury Science Focus Area.

Bacteria called methanotrophs feed off methane gas and can either take up or break down methylmercury, or both. Methanotrophs are widespread in nature and exist near methane and air interfaces, and both methane and methylmercury are usually formed in similar anoxic, or oxygen-deficient, environments.

To single out how and which methanotrophs perform demethylation, the ORNL-led team--along with methanotroph experts from the University of Michigan and Iowa State University--investigated the behavior of many different methanotrophs and used sophisticated mass spectrometry to analyze methylmercury uptake and decomposition by these bacteria. They discovered that methanotrophs such as Methlyosinus trichosporium OB3b can take up and break down methylmercury, while others such as Methylococcus capsulatus Bath only take up methylmercury.

In either case, the bacteria's interactions can lower mercury toxicity levels in water.

"If proven environmentally significant through future studies, our discovery of methanotrophs' behavior could be a new biological pathway for degrading methylmercury in nature," Gu said. This approach differs greatly from a previously recognized enzymatic pathway, which is only effective at very high mercury concentrations.

The methanotrophs identified in this study "open new opportunities to explore how nature detoxifies methylmercury and could improve our prediction of mercury toxicity levels and support better risk assessments and remediation efforts at mercury contamination sites," Gu added.
-end-
Co-authors of the paper titled, "Methylmercury uptake and degradation by methanotrophs," included ORNL's Xia Lu, Linduo Zhao and Baohua Gu; Wenyu Gu, Muhammad Farhan Ul Haque and Jeremy Semrau of the University of Michigan; and Alan DiSpirito of Iowa State University.

This research was funded by DOE's Office of Science, Office of Biological and Environmental Research, as part of the Mercury Science Focus Area at ORNL. ORNL is recognized as a leader for systematic studies of mercury in the environment.

UT-Battelle manages ORNL for DOE's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov/.

DOE/Oak Ridge National Laboratory

Related Methane Articles:

Microbial fuel cell converts methane to electricity
Transporting methane from gas wellheads to market provides multiple opportunities for this greenhouse gas to leak into the atmosphere.
Methane seeps in the Canadian high Arctic
Cretaceous climate warming led to a significant methane release from the seafloor, indicating potential for similar destabilization of gas hydrates under modern global warming.
Methane emissions from trees
A new study from the University of Delaware is one of the first in the world to show that tree trunks in upland forests actually emit methane rather than store it, representing a new, previously unaccounted source of this powerful greenhouse gas.
Oil production releases more methane than previously thought
Emissions of methane and ethane from oil production have been substantially higher than previously estimated, particularly before 2005.
Bursts of methane may have warmed early Mars
The presence of water on ancient Mars is a paradox.
New method for quantifying methane emissions from manure management
The EU Commision requires Denmark to reduce drastically emissions of greenhouse gases from agriculture.
New 3-D printed polymer can convert methane to methanol
Lawrence Livermore National Laboratory scientists have combined biology and 3-D printing to create the first reactor that can continuously produce methanol from methane at room temperature and pressure.
Arctic Ocean methane does not reach the atmosphere
250 methane flares release the climate gas methane from the seabed and into the Arctic Ocean.
Long-sought methane production mechanism identified
Researchers have identified the mechanism by which bacteria create methane, a potent greenhouse gas.
Retreat of the ice followed by millennia of methane release
Methane was seeping from the seafloor for thousands of years following the retreat of the Barents Sea ice sheet, shows a groundbreaking new study in Nature Communications.

Related Methane Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".