Description A new source of methane was recently discovered in a subsurface zone of the seabed, where the production and oxidation of methane occur concurrently. Preliminary work indicates that archaea and bacteria may here exchange electrons in the sediment through minerals that function as electrical conductors and capacitors. The working hypothesis is that the archaea are able to reverse the direction of their energy metabolism depending on whether they interact with electron accepting or electron donating bacteria. The specific objective is to unravel the processes using sensitive radiotracer experiments and to identify the microbial physiology of archaea involved in this ...
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Description Cable bacteria are filamentous microorganisms that transfer electrons across centimetre-scale distances, coupling distant oxidation and reduction reactions in aquatic sediment. Cable bacteria conserve energy by coupling the oxidation of hydrogen sulfide produced in deeper sediment layers to the reduction of oxygen diffusing into sediment from the overlying water. There is some evidence that under certain circumstances cable bacteria can reverse their oxygen reduction reaction in deep sediment, producing trace amounts of molecular oxygen from water. This oxygen then becomes available for respiration by aerobic bacteria in the surrounding sediment. This phenomenon has the potential to turn our concept of ...
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