| Budget Amount *help |
¥3,960,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥360,000)
Fiscal Year 2007: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2006: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
Biological methane oxidation at the oxic-anoxic interface in wetland soils and sediments is a key process in methane cycle, preventing large amounts of this greenhouse gas to escape into the atmosphere. A specific group of aerobic bacteria oxidises methane and is also able to assimilate methane-C. In limnic ecosystems, MOB (methane oxidising bacteria) are responsible for most of the methane oxidation, and they are also important in the surface layer of marine sediments. However, the fate of methanotrophic biomass is largely unknown. We demonstrate that an entire microbial food web can be driven by methane. Soil microcosms, in which a thin layer of water-saturated rice field soil was incubated under opposing gradients of oxygen and ^ (13) C-labelled methane, revealed ^ (13) C-enriched "heavy" RNA which could be affiliated to MOB, to the scavenging prokaryotic Myxobacteria, and to protistan grazers including amoebae, ciliates, and flagellates. Different protistan communities developed depending on methane concentrations. Protists isolated from the soil demonstrated selective grazing on MOB. Recent work using MOB as a model has shown that microbial community structure matters for ecosystem functioning. The results suggest that not only microbial, but also protistan diversity and microbe-protist interactions have to be considered.
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