Structural and Functional Links between Denitrifiers, Fermenters, and Methanogens: Impact on Greenhouse Gases
DFG FOR 562 TP 3: (2008-2011)
From 04/2008 to 12/2011Principal Investigator: Marcus A. Horn, Harold L. Drake
Staff: Katharina Palmer
Fens emit the greenhouse gases methane (CH4) and nitrous oxide (N2O). In the fen evaluated in the previous funding period, pore-water methane concentrations and methanogenic potentials were lower after experimental drying in 2006, whereas anaerobic CO2-production potentials, surface-near nitrate concentrations, and nitrous oxide emissions were higher. Thus, the methanogenic food chain and denitrification were affected by drying. 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 structure-function relationship of greenhouse-gas producing organisms in fens.