How are high rates of sulfate reduction associated with anaerobic oxidation of methane?

The association between high rates of sulfate reduction and anaerobic oxidation of methane is observed in environments where prokaryotes, such as certain types of bacteria and Archaea, thrive under anaerobic conditions. Sulfate-reducing bacteria and Archaea use sulfate as their final electron acceptor in anaerobic respiration, producing hydrogen sulfide. Alternatively, methanogens are a group of Archaea that reduce carbon dioxide to methane to generate energy and oxidize NADH.

This biological process is not only significant in natural cycles like the sulfur cycle, but also in contributing to and controlling levels of atmospheric methane, a potent greenhouse gas. Environments where these processes are active can be remarkably diverse, ranging from soil to the digestive tracts of ruminants, such as cows and sheep.

Methanotrophs, the bacteria and Archaea that utilize methane as their carbon source, play a crucial role in reducing environmental methane levels, thereby controlling its impact as a greenhouse gas. The intricate balance between methanogenesis and sulfate reduction in such anaerobic conditions impacts the overall carbon cycle and the local and global environment.