Methanogenic Degradation and Microbial Metabolism of Trace Gases

We want to learn which groups of soil microorganisms are responsible for particular biogeochemical processes and to understand the reason why. For this purpose we investigate biogeochemical processes involved in the exchange of climatically relevant trace gases (CH4, N2O, H2) between soil and atmosphere. A particular focus is on processes in flooded rice fields, which we have used during the last twenty five years as a model system for studying biogeochemistry and ecology of soil microbes.

Our experimental approach includes analytical chemical techniques and isotopic tracer studies (14C, 13C) for investigating the biogeochemical cycling of microbial substrates and effectors in soil. Similar techniques are used to investigate metabolic processes in microbial cultures, in particular studying stable isotope fractionation. Culture studies are the basis for the use of natural 13C abundance measurements to elucidate paths of C-flux. Another important experimental approach is the molecular characterization of rRNA genes and different functional genes for elucidating the composition of microbial communities, including transcript analysis and fluorescent in situ hybridization (FISH). Furthermore, stable isotope probing (SIP) of DNA and RNA allows the identification of metabolically active populations that incorporate 13C-labelled substrates.

For a brief research report describing the progress in the years 2010 and 2011, see: Methanogenic Degradation and Microbial Metabolism of Trace Gases