Paired microbes eliminate methane using sulfur pathwayJanuary 17, 2008Anaerobic microbes in the Earth's oceans consume 90 percent of the methane produced by methane hydrates - methane trapped in ice - preventing large amounts of methane from reaching the atmosphere. Researchers now have evidence that the two microbes that accomplish this feat do not simply reverse the way methane-producing microbes work, but use a sulfur compound instead. "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." Penn State | |||||||||||||||||||||
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Related Methane News Articles OU Researchers Isolate Microorganisms That Convert Hydrocarbons to Natural Gas When a group of University of Oklahoma researchers began studying the environmental fate of spilt petroleum, a problem that has plagued the energy industry for decades, they did not expect to eventually isolate a community of microorganisms capable of converting hydrocarbons into natural gas. Cataloguing invisible life: Microbe genome emerges from lake sediment When entrepreneurial geneticist Craig Venter sailed around the world on his yacht sequencing samples of seawater, it was an ambitious project to use genetics to understand invisible ecological communities. But his scientific legacy was disappointing - a jumble of mystery DNA fragments belonging to thousands of unknown organisms. Analysis of Lake Washington microbes shows the power of metagenomic approaches Today's powerful sequencing machines can rapidly read the genomes of entire communities of microbes, but the challenge is to extract meaningful information from the jumbled reams of data. New robot scouts best locations for components of undersea lab Like a deep-sea bloodhound, Sentry - the newest in an elite group of unmanned submersibles able to operate on their own in demanding and rugged environments - has helped scientists pinpoint optimal locations for two observation sites of a pioneering seafloor laboratory being planned off Washington and Oregon. Turning Waste Material into Ethanol Say the word "biofuels" and most people think of grain ethanol and biodiesel. But there's another, older technology called gasification that's getting a new look from researchers at the U.S. Department of Energy's Ames Laboratory and Iowa State University. By combining gasification with high-tech nanoscale porous catalysts, they hope to create ethanol from a wide range of biomass, including distiller's grain left over from ethanol production, corn stover from the field, grass, wood pulp, animal waste, and garbage. Rising energy, food prices major threats to wetlands as farmers eye new areas for crops Critical food shortages and growing demand for bio-fuels and hydro-electricity due to high fossil fuel prices rank among the greatest threats today to the preservation of precious wetlands worldwide as farmers and developers look for new areas for agriculture, energy crop plantations and hydro dams. Cow power could generate electricity for millions Converting livestock manure into a domestic renewable fuel source could generate enough electricity to meet up to three per cent of North America's entire consumption needs and lead to a significant reduction in greenhouse gas emissions (GHGs), according to US research published today. Massive greenhouse gases may be released as destruction, drying of world wetlands worsens: UN Leading world scientists convene in Brazil July 21-25 amid growing concern that evaporation and ongoing destruction of world wetlands, which hold a volume of carbon similar to that in the atmosphere today, could cause them to exhale billows of greenhouse gases. Fuel from food waste: bacteria provide power Researchers have combined the efforts of two kinds of bacteria to produce hydrogen in a bioreactor, with the product from one providing food for the other. Do the hyper-coordinate planar transition metal atoms exist? A study reported in Vol 51, Issue 7 (July, 2008) of Science in China Series B: Chemistry has shown that wheel-shaped structures with octa- and enneacoordinate planar cobalt, iron and nickel centered in perfect octagonal and enneagonal boron rings, are stable on corresponding potential hyper-surfaces. This suggests that the central element bonding capacities have not been exhausted. More Methane News Articles |
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