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Nitrogen Fixation




Nitrogen fixation is performed naturally by a number of different Prokaryote s, including Bacteria , and Actinobacteria certain types of Anaerobic bacteria. Many higher plants, and some animals ( Termite s), have formed associations with these microorganisms.


BIOLOGICAL NITROGEN FIXATION

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Biological Nitrogen Fixation (BNF) occurs when atmospheric nitrogen is converted to ammonia by a bacterial enzyme called Nitrogenase . Microorganisms that fix nitrogen are called Diazotroph s. The formula for BNF is:

: N2 + 8H+ + 8e- + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi

Although Ammonia (NH3) is the direct product of this reaction, it is quickly ionized to Ammonium (NH4+). In free-living diazotrophs, the nitrogenase-generated ammonium is assimilated into Glutamate through the glutamine synthetase/glutamate synthase pathway. Biological nitrogen fixation was discovered by the Dutch microbiologist Martinus Beijerinck .


LEGUMINOUS NITROGEN-FIXING PLANTS

The best-known are Legume s (such as Clover , beans, alfalfa and peanuts,) which contain Symbiotic bacteria called Rhizobia within Nodules in their Root Systems , producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the nitrogen helps to fertilize the Soil . The great majority of legumes have this association, but a few genera (e.g., '' Styphnolobium '') do not.


NON-LEGUMINOUS NITROGEN FIXING PLANTS

Plants from many other families have similar associations, including:


CHEMICAL NITROGEN FIXATION

Nitrogen can also be artificially fixed for use in Fertilizer , explosives, or in other products. The most popular method is by the Haber Process . Artificial fertilizer production has achieved such scale that it is now the largest source of fixed nitrogen in the Earth 's Ecosystem .


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