What are the conditions necessary for the fixation of atmospheric nitrogen by Rhizobium? What is their role in nitrogen fixation?
Rhizobia are unique because they live in a symbiotic relationship with legumes. Necessary conditions: Requires a strong reducing agent and energy in the form of ATP. The enzyme nitrogenase which is very sensitive to oxygen is required. The processes take place in an anaerobic environment The energy is provided by the respiration of host cells. The reduction of nitrogen to ammonia by living organisms is called biological nitrogen fixation. The enzyme, nitrogenase which is capable of nitrogen reduction is present exclusively in prokaryotes. Several types of symbiotic biological nitrogen-fixing associations are known. The most common association on roots is nodules Their role in N2– fixation is to supply the plants with nitrogenase that converts nitrogen to amino acids.
