Nitrogenase Activity in Cyanobacterial Biofilm

The nitrogenase activity could be detected in cyanobacteria only when there is a special or temporal separation of photosynthesis and nitrogen fixation. We could induce the activity of nitrogenase in a few isolates of Oscillatoria, O. sancata is best in forming cyanobacterial biofilm with other heterocystous cyanobacteria. The activity of nitrogenase was detected when nitrate grown cells were starved for combined nitrogen for 1 to 15 days and grown in low light intensity of 6.022 x 10¹⁷ photons s⁻¹ m⁻². Therefore it appears that non-heterocystous cyanobacteria could very well participate in rice field N₂ fixation. Perhaps it is necessary to have an indepth study of non-heterocystous forms to select ideal strains for use as biofertilizer mixed with heterocystous forms to make biofilm for higher nitrogen fixation in biofertilizer programme in wet land crops.