nitrogen fixation

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ni·tro·gen fix·a·tion

process in which atmospheric nitrogen is converted to ammonia.
Farlex Partner Medical Dictionary © Farlex 2012

nitrogen fixation

n.
1. The conversion of atmospheric nitrogen into compounds, such as ammonia, by natural agencies or various industrial processes.
2. The conversion by certain soil microorganisms, such as rhizobia, of atmospheric nitrogen into compounds that plants and other organisms can assimilate.

ni′tro·gen-fix′er (-fĭk′sər) n.
ni′tro·gen-fix′ing adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

nitrogen fixation

the utilization of atmospheric nitrogen in the synthesis of AMINO ACIDS by some bacteria. Such bacteria can be free-living (e.g. Azotobacter, an aerobe; Clostridium, an obligate anaerobe) while others (e.g. Rhizobium) live in association with plants, occupying swellings in the root called root nodules. The latter relationship is one of SYMBIOSIS, in that the plant gains nutrients and thus can live in nitrogen-poor soils, while the nitrogen-fixer obtains a supply of carbohydrates from the plant. The nitrogen is reduced to ammonia in the microbes by action of the enzyme nitrogenase: N2 + 3 H22 NH3, the ammonia then reacting with keto acids to form amino acids.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Along the way, the research team discovered a novel nitrogen fixation process.
Biological nitrogen fixation process supplies greater than 60% nitrogen in pulse crop (Evans, 2005).
This nitrogen fixation process also permitted the development of TNT, and Haber himself used it to create the ultimate weapon of his time, poison gas.