Bacterial Siderophores for Enhanced Plant Growth

The soil is a repository of microorganisms such as bacteria, fungi, algae, and protozoa. Among these, more bacteria are found, most of which are located in the rhizosphere region of the soil. The rhizosphere, under the direct control of plant root secretions, is the complex, narrow area of the soil. It is densely populated with microorganisms (mostly bacteria) that interact with the plants. These interactions influence the growth of the plant directly or indirectly. Plant growth-promoting rhizobacteria (PGPR) inhabiting the rhizosphere colonizes the plant roots and increases plant growth via different mechanisms. Iron is an essential micronutrient required by almost all life forms including plants. Oxidation of Fe2+ (soluble) to Fe3+ (insoluble) due to the soil's aerobic conditions limits its bioavailability. Siderophores are selective low molecular weight ferric ion chelators secreted by bacteria to acquire iron from the surrounding. They bind to iron (Fe3+) with high specificity as well as high affinity. By helping the insolubilisation of iron, it promotes the growth and yield.