Anaerobic oxidation of methane
Atmospheric methane (CH4) is the second most important greenhouse gas after CO2. Anaerobic oxidation of methane (AOM) plays a major role in the sub-seafloor methane flux and in marine sediments. The main sources for methane production in ocean sediments are thermogenic methane formation and microbial methane formation in past and present. Also methane hydrates at the seafloor are releasing methane to the seawater and consequently to the atmosphere. Methane can be degraded by means of microbial oxidation under both aerobic and anaerobic conditions.
Current research revealed that methane diffusing upwards from deep sites of sediments often disappears before any contact with oxygen is possible and microorganisms are thought to consume methane in such anoxic zones. The amount of methane consumed by anaerobic methane oxidation each year is approximately equivalent to 5 to 20% of the total annual methane flux to the atmosphere. However, the microorganisms responsible for this process have not yet been isolated. Only quite recently, it was found that the process might be catalyzed by a consortium of organisms. In our laboratory we carry out research to get detailed insight into bacterial AOM at both moderate and high temperature conditions. Isolation efforts are performed under different conditions like micro-aerophillic and high pressure (100 bar). highly enriched sludge in a membrane bioreactor is used for developing molecular tools for detecting these very slow growing organisms.
Anaerobic methane oxidation for biological sulfate & sulfur reduction