Blue Green Algae and Azolla,Cyanobacteria,Prokaryotic Organisms,Heterocysts,Anabena Azollae

	Blue Green Algae and Azolla - Blue-green algae (cyanobacteria) are photosynthetic, prokaryotic organisms, which fix N2 asymbiotically; some cyanobacteria are known to form symbiotic associations, e.g., Azolla (a fem)-Anabena azollae (a blue green alga). Examples of cyanobacteria are Anabaena, Nostoc, Plectonema, etc. Usually, composite cultures containing two or more genera are used for field inoculation since they are often superior to single strain inoculations.
Cyanobacteria produce nitrogenase and N2-fixation occurs in specialized structures called heterocysts, in which the nif region becomes reorganized (this is essential for N2-fixation). In addition, heterocysts act as 02-proof compartments, which protect nitrogenase from 02 inactivation. Cyanobacteria are useful in reclaimation of alkaline soils, and they are used for rice. Azolla owes its N2-fixing capability to the symbiont Anabaena azollae. Azolla is widely used in Vietnam as biofertilizer for rice.
It has not become popular in India due to its sensitivity to high temperature (during summer), necessity for assured and adequate water supply and susceptibility to insects and diseases. Cyanobacteria, are useful in reclaimation of alkaline soils, and they are used for rice.