Abstract
The cycles of three elements, nitrogen, sulphur and carbon in the biosphere of the earth have been described with special reference to the bacteria which utilizes the inorganic compounds of the elements.
Ammonia is oxidized to nitrate by a coaction of the ammonia- and nitrite-oxidizing bacteria, the resulting nitrate is changed into nitrogen gas by the denitrifying bacteria. Nitrogen gas is reduced to ammonia by biological and industrial nitrogen fixations. Sulphate is reduced to hydrogen sulphide and this compound is oxidized to elemental sulphur or sulphate by the sulphur-oxidizing bacteria and photosynthetic sulphur-oxidizing bacteria. Finally, carbon dioxide is changed into organic compounds mainly by algae, while the gas is partially reduced to methane by methanogenic bacteria. Methane can be partially trapped by a coaction of the ammonia-oxidizing bacteria and C1 compound-utilizing bacteria.
