Structural and Functional Links between Denitrifiers, Fermenters and Methanogens: Impact on Greenhouse Gases

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Fens emit the greenhouse gases methane (CH4) and nitrous oxide (N20). In the fen evaluated in the previous funding period, pore-water methane concentrations and methanogenic potentials were lower after experimental drying and rewetting in 2006, whereas anaerobic CCVproduction potentials, surface-near nitrate concentrations, and nitrous oxide emissions were higher. Thus, the methanogenic food chain and denitrtfication were affected by drying and rewetting. The new objectives of the next funding period are to identify the effect of intensified drying and rewetting, as well as flooding on the structure and activity of (i) fermenters, (ii) methanogens, and (iii) denitrifiers. Denitrifier diversity will be identified by functional gene analysis (narG and nosZ) and cultivation methods. Novel organisms will be ecophysiologically characterized and taxonomically validated. Comparative mRNA and DNA based T-RFLP analyses of functional genes, qPCR, and 16S rRNA-based microarray analyses will be used to detect changes in community structure of active organisms. Michaelis-Menten-kinetics of fermenters, methanogens, and denitrifiers will be applied to identify community structure-related activity changes and thus elucidate structurefunction relationship of greenhouse-gas producing organisms in fens.