Screening of siderophore-producing salt-tolerant rhizobacteria suitable for supporting plant growth in saline soils with iron limitation

Iron (Fe) bioavailability to plants is reduced in saline soils; therefore, plants growing in arid soils face two major challenges for poor crop productivity: high salinity and Fe deficiency. Siderophore-producing plant growth-promoting rhizobacteria (PGPR) could be a promising alternative to chemical fertilizers that could tackle salt stress and Fe limitation in saline soils concurrently. Here, four salt-tolerant PGPR, isolated from the root area of salt-prone rice fields of Bangladesh were studied to evaluate their siderophore-producing ability. Bacillus aryabhattai MS3 exhibited the highest production, estimated at 60% and 43% under non-saline and saline (200 mM NaCl) conditions respectively. The expression of the entD gene, which is involved in the biosynthesis of siderophore was evidenced irrespective of saline states. Therefore, consideration of such salt-tolerant, siderophore-producing PGPR for producing biofertilizer could be an eco-friendly innovation for climate-smart agriculture in salinized soils with limited iron availability.