ENVS 1100 Lecture Notes - Nitrogenase, Leghemoglobin, Rhizobium
Document Summary
Nitrogen represents 78% of air and is the main source of this element. It can be found in gaseous or mineral form. For its incorporation into biological molecules, we distinguish two processes: biological fixation, which is the sole prerogative of nitrogen- fixing microorganisms, and non-biological fixation, which involves mineral nitrogen. Regardless of its initial form, nitrogen is converted into ammonia or ammonium ion, which is then transformed into amine or amide functions. Biological nitrogen fixation is the most important biochemical process after co2 assimilation. It ensures the transformation of atmospheric nitrogen gas into ammonia. Only a few diazotrophic microorganisms are capable of carrying out this process, among which are distinguished. Free-living bacteria in soil (klebsiella and azotobacter), cyanobacteria (blue-green algae). Rhizobacteria, symbiotic bacteria living in association with legumes in organized root or stem structures called nodules. These bacteria and some yeasts are capable of reducing nitrogen according to the overall reaction:
