Nitrogen fixation, biological

Biological nitrogen fixation is the reduction of dinitrogen (N2) to ammonia (NH3). The reaction can be represented as:

N2 + 3H2 = 2NH3

The process is catalysed by the enzyme nitrogenase and is conducted by a large range of nitrogen-fixing bacteria such as Rhizobium and cyanobacteria. A broad range of environmental and biochemical factors can affect the nature and extent of nitrogen fixation within a particular environment or system. Light, water temperature, pH, salinity, dissolved oxygen, trace elements, inorganic nitrogen and organic substrate availability have all been shown to modulate nitrogenase activity in specific situations [2].

  1. Postgate, J.R. 1998. Nitrogen Fixation. 3rd Edition. Canbridge University Press, London.
  2. Capone, D.G. 1988. Benthic Nitrogen Fixation. In: Blackburn, T.H. and Sorensen, J. (eds.) Nitrogen Cycling in Coastal Marine Environments, pp. 85-123. Wiley & Sons, New York.
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