What are the conditions necessary for fixation of atmospheric N2 by Rhizobium ? What is their role in N2 fixation.

Conditions for N2 fixation : There are following conditions necessary for N2 fixation :

(1) A strong reducing agent like NADPH : It supplies hydrogen to N2.

(2) ATP as source of energy : It provides energy. For fixation of NH3 molecules, 8 ATP molecules are needed.

(3) The enzyme system : Nitrogenase is necessary for N2 fixation.

(4) Compound for trapping ammonia : Ammonia is very toxic and needs to be trapped in the form of amino acids.

(5) Leghaemoglobin : It is O2 scavenger and maintains anaerobic environment otherwise in the presence of O2 the enzyme nitrogenase is toxicated.