"MUMM - Methane in the Geo/Bio-System - Turnover, Metabolism and Microbes" is a project of the BMBF/DFG initiative " Geotechnologies - A geoscientific research and development programme".

Project Description

Objectives

The objectives of the proposed project are:

1. The in situ quantification of microbial turnover and transport processes in methane-rich GeoBio-systems
2. The experimental investigation of the regulating factors of methane turnover and microbial growth in bioreactors
3. The in situ identification of the biodiversity and distribution of methane-consuming microorganisms from diagnostic organic molecules and nucleotide sequences
4. The investigation of key enzymes and metabolic functioning of anaerobic methane oxidizers

Rationale

The oxidation of methane by anaerobic microbes is a significant process in the global carbon cycle and a major sink for methane on earth. The anaerobic oxidation of methane (AOM) effectively controls the emission of methane to the hydrosphere by converting more than 90% of the methane produced in marine sediments before it enters the hydrosphere and atmosphere. AOM therefore plays an important role in the regulation of the greenhouse gas methane. During AOM, methane is oxidized with sulfate as the terminal electron acceptor, so far known mediated by a consortium of methane-oxidizing archaea and sulfate-reducing bacteria. These microorganisms were identified for the first time in 1999 in methane rich sediments above gas hydrate. Despite intensive international effort, these microorganisms are still not available in culture. Hence, the biochemical pathways, controlling mechanisms, and mediating organisms of the process still bear many unknowns. However, at the MPI we have achieved enrichment of the three main phylogenetic groups of methanotrophic microorganisms (Boetius et al. 2000, Michaelis et al. 2002, Lösekann et al. unpublished results). During the first MUMM project (2001-2003) we have identified several factors critical to understanding and quantifying microbial turnover, diversity and regulation. The main factor is the methane flux and availability of sulfate as electron acceptor. Hence, the main aim of this study is still the quantification of methane and its oxidation at the bottom of the ocean, using modern in situ techniques. A new development is the expertise of the MPI in environmental genomics and proteomics, which has already lead to the first major discovery of a new enzyme (Krüger et al. 2003).We plan field studies of gas hydrate bearing sediments in oxic and anoxic marine environments, as well as of locations of high and low flux of methane to the hydrosphere.
These field studies will be planned and carried out in cooperation with the projects METRO (field sites in the Black Sea) and COMET (Cadiz, New Zealand) as well as with other cooperation partners such as AWI (Barents Sea), IFREMER (Eastern Mediterranean), University of Georgia and Texas A&M (Gulf of Mexico).
The investigation of many different GeoBio-systems has resulted in significant knowledge on the diversity of methanotrophs and is still the main key to the understanding of the evolution and change of methane driven habitats.