Description:
Methane, also known as natural gas, is produced biologically from carbon dioxide by a series of 2-electron reductions in a process known as methanogenesis. It is estimated that 1015g methane is produced annually by methanogenic bacteria, or methanogens, worldwide. Methanogens are strictly anaerobic and produce methane in environments such as sediments, rice paddies and the guts of ruminant organisms. In some environments, such as lakes, it has been observed that 90% of biogenic methane is oxidized before reaching the atmosphere. Methane is biologically oxidized in aerobic environments, such as the upper regions of lakes, by a series of 2-electron oxidation reactions known collectively as methanotrophic metabolism, or methanotrophy. The environmental coupling of methanogenesis and methanotrophy leads to a high turnover global cycle of C1 compounds. C1 fragments from many sources are metabolized by disparate bacteria and ultimately feed into the global C1 cycle shown below. EAWAG-BBD pathways frequently produce C1 compounds. Links to many of them are found at the bottom of C1 compound pages.