http://web.uconn.edu/mcbstaff/benson/Frankia/NitrogenaseCartoon.jpg

http://www.physicalgeography.net/fundamentals/images/nitrogencycle.jpg

http://www.marietta.edu/~biol/102/ncycle.gif

Assimilatory Nitrate Reduction in Hfx mediterranei .
All the enzymes in the figure have been purified and characterised except glutamate synthase. Nas: assimilatory nitrate reductase; NiR: assimilatory nitrite reductase; Fd: Ferredoxin; GDH: glutamate dehydrogenase; GS: glutamine synthetase; GOGAT: glutamate synthase.
Bonete et al. Saline Systems 2008 4 :9 doi:10.1186/1746-1448-4-9

http://www.fao.org/docrep/field/003/R7740E/R7740E02.htm

Anabaena http://www.marietta.edu/~spilatrs/biol202/microid/ImageFinder.php

http://life.bio.sunysb.edu/marinebio/pl_11.jpg

http://www.usc.edu/dept/LAS/biosci/Webb_lab/Projects_files/droppedImage.png

The Haber–Bosch process is the reaction of nitrogen and hydrogen to produce ammonia.
The nitrogen (N
2
) and hydrogen (H
2
) gases are reacted over an iron catalyst (Fe 3+ ) and aluminium oxide (Al
2
O
3
) and potassium oxide (K
2
O) are used as promoters. The reaction is carried out under conditions of 250 atmospheres (atm), 450-500°C; resulting in a yield of 10-20%:
N
2
(g) + 3H
2
(g) ? 2NH
3
(g) + ? H (Where ? H is the heat of reaction or enthalpy. For the Haber process, this is -92.4 kJ/mol at
25°C)
The process was first patented by Fritz Haber in 1908. In 1910
Carl Bosch, while working for chemical company BASF, successfully commercialized the process and secured further patents. http://en.wikipedia.org/wiki/Haber_process

The Haber process now produces 100 million tons of nitrogen fertilizer per year, mostly in the form of anhydrous ammonia, ammonium nitrate, and urea.
1% of the world's annual energy supply is consumed in the Haber process (Science
297(1654), Sep 2002).
That fertilizer is responsible for sustaining
40% of the Earth's population.
http://en.wikipedia.org/wiki/Haber_process

http://www.tau.ac.il/~ecology/virtau/2-tali/Examples%20from%20nature_files/nitro.gif

Molecular Biology and Evolution
NifH Phylogeny http://www.stat.rice.edu/~siefert/Raymondetsl2004.pdf

Proposed gene versus species trees http://www.stat.rice.edu/~siefert/Raymondetsl2004.pdf

http://www.biology.wustl.edu/faculty/kranz/cascade.gif

Methanogenesis http://www.mumm-research.de/images/biochem_fig4.jpg