Ammonia nitrogen-fixing bacteria

Only certain prokaryotes can fix atmospheric nitrogen. These include the cyanobacteria of soils and fresh and salt waters, other kinds of free-living soil bacteria such as Azotobacter species, and the nitrogen-fixing bacteria that live as symbionts in the root nodules of leguminous plants. The first important product of nitrogen fixation is ammonia, which can be used by all organisms either directly or after its conversion to other soluble compounds such as nitrites, nitrates, or amino acids. 

E. Kayser and H. Delaval observed that the presence of a radioactive uranium mineral increased the activity of nitrogen-fixing bacteria. A. W. Bosworth and co-workers observed that ammonia is produced by the human tubercle bacillus. 

In nature, ammonia is produced by the action of nitrogen-fixing bacteria on atmospheric N2 under very mild conditions (room temperature and 0.8 atm N2 pressure). These bacteria contain nitrogenases, iron- and molybdenum-containing enzymes that catalyze the formation of NH3. Industrially, NH3 is synthesized from its elements by the Haber-Bosch process, which typically uses finely divided iron as catalyst ... 

Nitrogen fixation Nitrogen can be fixed for plants in three ways by lightning, by nitrogen-fixing bacteria living in the roots of plants or in the sod, and by commercial synthesis reactions such as the Haber ammonia process. 

In 1960 a group of microbial biochemists in the Central Research Laboratories of the Dupont de Nemours Chemical Corporation, USA, broke through a barrier that had impeded researchers for at least two decades. They extracted from a species of nitrogen-fixing bacteria a solution containing the enzyme which is responsible for the activation of dinitrogen." It was called nitrogenase, and, in appropriate conditions, it bound N2 from the atmosphere and reduced it to ammonia. 

Nitrosomonas oxidizes ammonia to nitrite and Nitrobacter oxidizes nitrite to nitrate. Other bacteria, the denitrifying bacteria, convert ammonia to N2-just the opposite of the nitrogen-fixing bacteria. 

Haber process nitrogen fixation nitrogen-fixing bacteria denitrification nitrogen cycle ammonia hydrazine nitric acid Ostwald process... 

Nitrogen-fixing bacteria bacteria in the root nodules of plants that can convert atmospheric nitrogen to ammonia and other nitrogen-containing compounds useful to plants. (20.2)... 

The nitrogenase enzyme complex found in nitrogen-fixing bacteria catalyzes the production of ammonia from molecular nitrogen. The half-reaction of reduction (Figure 23.2a) is... 

The participation of ammonia in the nitrogen cycle is a most important natural process. Nitrogen-fixing bacteria ate able to achieve similar reactions to those of the Haber process, but under normal conditions of temperature and pressure. These release ammonium ions, which are converted by nitrifying bacteria into nitrite and nitrate ions. 

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