W Washington, May 15 : A team of scientists has made a breakthrough in capturing microorganisms that are known to dramatically reduce the oceanic emission of methane into the atmosphere.  Dr Annelie Pernthaler of the Helmholtz Centre for Environmental Research (UFZ) in Leipzig says that, along with her colleagues from the California Institute of Technology (Caltech) in Pasadena, she has developed a new molecular technique to selectively separate the so-called syntrophic (meaning "feeding together") microorganisms from their natural complex community, and subsequently sequence their genome. In addition to identifying all genes responsible for the anaerobic oxidation of methane, the researchers have also discovered new bacterial partners of these microorganisms. During their research, Pernthaler and co-workers attached small ironbeads to the microorganisms of interest, and pulled them out of the deep-sea sediment by simply applying a magnet. The researchers revealed that the microbes were Archaea, which cooperate with sulfate reducing Bacteria to perform a thermodynamically tricky process: the anaerobic oxidation of methane (AOM). A research article being published in PNAS suggests that these poorly understood consortia are globally distributed in oceanic sediments above methane hydrates, and provide a significant sink for methane by substantially reducing the export of this potent greenhouse gas into the atmosphere. Upon sequencing the genomes of the purified syntrophic consortia, the research team was able to identify all genes responsible for AOM. Pernthaler and her colleagues also discovered an unexpected diversity in the bacterial partners of this syntrophic association, which may play a role in the performance of AOM. Besides this, the researchers also showed in lab experiments that the AOM archaea were indeed fixing N2. The significance of the new findings lies in the fact that the fixation of N2 is energetically expensive processes, and that the energy gained by AOM is low. The potential for metabolic versatility combined with the ability to form partnerships with other microorganisms, might be the secret to the successful distribution of this biogeochemically significant group of microorganisms. (ANI) © 2007 ANI TAGS: Science 
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