What are the conditions necessary for fixation of atmospheric nitrogen by Rhizobium. What is their role in N२-fixation?
Rhizobia fix atmospheric nitrogen and live in symbiosis (a mutual relationship in which both get benefited) with the leguminous plants who provide sugar and starch to the bacteria. Certain conditions are necessary for the fixation of atmospheric nitrogen by Rhizobium: Nitrogenase enzyme must be present.A reducing environment must be present.Leghaemoglobin must be present.ATP should be present as a source of energy.An electron donor ferredoxin must be present.Magnesium ions as cofactors must be present. The nitrogenase enzyme is a Mo-Fe protein that is present in Rhizobium and it helps in the fixation of atmospheric nitrogen(N2) into ammonia (NH3). The reducing environment is needed for the nitrogenase enzyme as it is sensitive to free oxygen. This enzyme is protected from the free oxygen by leghaemoglobin which is present in the root nodules of the plant. The nitrogen fixation requires ATP as an energy source as the process is energy-requiring. Ferredoxin is a non-haem iron protein that makes
