Siderophore production in Anabaena oryzae was investigated under the influence of various levels of iron and other abiotic factors such as pH, temperature, light and different nitrogen sources. Optimization of culture conditions under controlled mechanisms of these abiotic factors lead to the siderophore production in significant amount. Under iron-starved condition, A. oryzae extracellularly releases 89.17 % hydroxymate-type siderophore. Slightly alkaline pH and 30 degrees C temperature was found stimulatory for the cyanobacterial growth and siderophorogenesis (88.52 % SU and 83.87 % SU, respectively). Excess iron loading had a negative impact on siderophore production along with the alterations in the morphology and growth. Further, scanning electron microphotographs signified that higher concentrations of iron lead to complete damage of the cells and alterations in membrane proteins possibly transporters responsible for exchange of siderophore complex from environment to the cell. SDS-PAGE analysis of whole cell proteins showed overexpression of low molecular weight proteins ranges between 20.1 to 29.0 kDa up to 100-mu M iron concentrations. These polypeptides/proteins might be involved in maintaining iron homeostasis by regulating siderophore production. Results suggest that lower concentrations of iron <= 50 mu M along with other abiotic factors are stimulatory, whereas higher concentrations (> 50 mu M) are toxic. Data further suggested that cyanobacterium A. oryzae can serve as a potential biofertilizer especially in iron-rich soil through sequestration by the power of natural Fe(III)-siderophore complex formation.