By identifying two genes required for transforming inorganic into organic mercury, which is far more toxic, scientists today have taken a significant step toward protecting human health.
The question of how methylmercury, an organic form of mercury, is produced by natural processes in the environment has stumped scientists for decades, but a team led by researchers at Oak Ridge National Laboratory has solved the puzzle. Results of the study, published in the journal Science, provide the genetic basis for this process, known as microbial mercury methylation, and have far-reaching implications.
"Until now, we did not know how the bacteria convert mercury from natural and industrial processes into methylmercury," said ORNL's Liyuan Liang, a co-author and leader of a large Department of Energy-funded mercury research program that includes researchers from the University of Missouri-Columbia and University of Tennessee.
"This newly gained knowledge will allow scientists to study proteins responsible for the conversion process and learn what controls the activity," said Liang, adding that it may lead to ways of limiting methylmercury production in the environment.
For some 40 years scientists have known that when mercury is released into the environment certain bacteria can transform it into highly toxic methylmercury. Exactly how bacteria make this happen has eluded scientists. The challenge was to find proteins that can transfer a certain type of methyl group and to identify the genes responsible for their production.
Ultimately, by combining chemical principles and genome sequences, the team identified two genes, which they named hgcA and hgcB. Researchers experimentally deleted these genes one at a time from two strains of bacteria, which caused the resulting mutants to lose the ability to produce methylmercury. Reinserting these genes restored that capability, thus verifying the discovery.
The researchers found that this two-gene cluster is present in all known mercury-methylating bacteria, and they predicted that more than 50 other microorganisms may methylate mercury because they have a pair of similar genes.
Another key to the development was the collection of talent assembled to work on this problem.
"This discovery was made possible by our diverse team, which includes scientists with expertise in chemistry, computational biology, microbiology, neutron science, biochemistry and bacterial genetics," said Liang, who rated this paper as one of the most satisfying of her career.
Mercury is a toxin that spreads around the globe mainly through the burning of coal, industrial use and through natural processes such as volcanic eruptions. The chemical element bioaccumulates in aquatic food chains, especially in large fish. Various forms of mercury are widely found in sediments and water.
In a report just released by the United Nations Environmental Programme, Achiim Steiner, United Nations under-secretary general and executive director of UNEP, notes that "mercury remains a major global, regional and national challenge in terms of threats to human health and the environment."
DOE/Oak Ridge National Laboratory: http://www.ornl.gov
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Swallowing a sulfur-rich protoplanet could help explain two lingering mysteries in the story of Earth's formation
In a first-of-its-kind endeavor, electricity-starved Rwanda and the Democratic Republic of Congo are trying to get power from a lake—and avert catastrophe.It’s a Friday afternoon on the Rwandan side of Lake Kivu, and in what was once a quiet cove, a daring venture is taking shape.
The good news is that an eruption there is highly unlikely, but the bad news is that it would be huge
Flame-retardant fabrics normally degrade when washed, but a water-repelling coating could make your flame-proof suit or sofa self-cleaning
It may look like nothing more than a small ball of metal, but the shape-shifting and self-propulsion abilities of a liquid metal alloy discovered by scientists at China's Tsinghua University has captured the imaginations of scientists and science-fiction fans across the world.
The same receptor on nerve endings that makes sinuses tingle when we eat wasabi plays an important role in the pain of inflammation. The first 3-D view of the receptor could lead to better pain drugs.
As the craft beer industry grows, so are options for learning to brew. More colleges are now introducing degree programs to teach the art and science of beer-making.
Researchers were surprised by what they found when they sandwiched a drop of water between two layers of an unusual two-dimensional material called graphene.
Scientists at Cern are suggesting they could soon detect miniature black holes, proving the existence of parallel universes and disproving the big bang theory of the creation of the universe.
The Curiosity rover makes a detection of nitrogen compounds which provide further evidence that ancient Mars would have been a habitable world.