"The dominant role anaerobic oxidation of methane plays in regulating marine methane makes it a significant component of the global methane and carbon cycles," the researchers report in the current issue of Environmental Microbiology. "Its importance in these cycles highlights the need to close gaps in the current understanding of the specific interaction between the microbial groups that work in consort to mediate anaerobic oxidation of methane."
In this case, the microbial consortia consist of an Archaea – a single cell organism – that consumes methane for energy and bacteria that reduce sulfates to obtain energy. The assumption has been that these microbes simply use reverse methanogenesis, the process in which methanogenic bacteria produce methane in the first place.
"Our research suggests that methyl sulfide is the intermediary used by these microbes," says Christopher H. House, associate professor of geosciences. "The Archaea take in the methane and produce a methyl sulfide, and then the sulfur-reducing bacteria eat the methyl sulfide and reduced it to sulfide."
The two single-celled organisms that live in the consortia arrange themselves in a cluster of about 100 cells 10 to 15 microns across. The microbes that consume methane are on the inside while those microbes-reducing sulfur are on the outside. These consortia live in the sediments on the ocean bottom around methane seeps.
Understanding how these symbiotic organisms remove methane from the oceans is important because, House notes that without these microbes, the atmospheric temperature would likely be warmer by about 14 degrees Fahrenheit.
House, working with James J. Moran, graduate student in geosciences now at McMaster University; Emily J. Beal, graduate student in geosciences; Jennifer M. Vrentas, a Penn State undergraduate at the time; Katherine Freeman, professor of geosciences, all at Penn State, and Victoria J. Orphan, assistant professor of geobiology, California Institute of Technology, first investigated the assumption that reverse methanogenesis was the method used by the microbes. They provided hydrogen to the consortium and checked to see if methane oxidation decreased. If hydrogen were the interspecies transfer molecule, than an abundance of hydrogen would turn off the methane oxidation.
"We observed a minimal reduction in the rate of methane oxidation, and conclude that hydrogen does not play an interspecies role in anaerobic oxidation of methane," the researchers say.
They then tried the methyl sulfides, methanethiol (methyl mercaptan) and dimethyl sulfide, to see if they reduced methane oxidation. The researchers found that methanethiol reduced oxidation. The researchers also substituted carbon monoxide for methane and found that the Archaea could oxidize that as well and produce these sulfur compounds.
"In climate models, researchers generally only consider the methane produced in bogs and lakes as dominant greenhouse gases," says House. "They do not need to consider ocean methane because these microbes destroy most of it before it is released from the sediments."
A'ndrea Elyse Messer | EurekAlert!
NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center
Steep rise of the Bernese Alps
24.03.2017 | Universität Bern
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
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