Diel cycle of nitrogen fixation

Possible that the cycle of nitrogen fixation is due to a circadian rhythm. Day-advantage: Use energy/reductants from photosynthesis. Night: present as high molecular mass form (inactive) and is determined by how much fixation occurs. Light: cause initiation of synthesis and return of the Fe protein to the active low molecular mass. Modification in inactive from occurs in O2 presence. Fe protein could play a role in protection of nitrogenase from inactivation by O2 but not simultaneous photosynthesis/fixation.