Siderophore –The Iron Chelator Production Potential of Bacteria Associated with Diverse Crops and Growth Medium Optimization for its High Production

Siderophores (in Greek: iron carriers) are low molecular weight compounds produced under iron-limiting conditions by microorganisms that chelates Fe3+ (ferric iron) with high specific activity, which in turn make it available to the plant system. Selection of efficient siderophore producing plant associated bacteria and their potential role in enhancing plant iron uptake is a strategic approach for improving plant health as Fe is an integral component and cofactor for many biomolecules. In the present study 154 bacteria associated with maize, mustard and sugarcane as endophytic or rhizospheric isolates, on screening led to the identification of 24 efficient siderophore producers (Sid+) with siderophore producing index (SPI) of 1.03-1.70 and the concentration from 0.1 to 11.25 µg/ml in Fiss glucose medium. For higher siderophore production optimization minimal and complex media were tested. Barbhaiya and Rao medium (BR), a minimal medium improved siderophore production ranging from 02.54 – 15.65 µg/ml. Complex malt extract medium produced 0.27-2.44 µg/ml of siderophores and was found to have least influence on siderophore production irrespective of bacterial culture. Differential sugars utilization pattern of 35 sugars tested was recorded with different isolates. A formulation of such siderophore producing bacterial isolates can be used for improving micronutrients availability for the plant to be more healthy and productive.