Chemolithotrophy is a type of metabolism found in prokaryotes where energy is obtained from the oxidation of inorganic compounds. These organisms can use hydrogen,[45] reduced sulfur compounds (such as sulfide, hydrogen sulfide and thiosulfate),[1] ferrous iron (FeII)[46] or ammonia[47] as sources of reducing power and they gain energy from the oxidation of these compounds with electron acceptors such as oxygen or nitrite.[48] These microbial processes are important in global biogeochemical cycles such as acetogenesis, nitrification and denitrification and are critical for soil fertility.[49][50]