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Under scarce iron conditions, several bacteria, fungi and plants, secrete ferric iron-specific ligands, generically termed as siderophores that are able to bind with insoluble ferric ion thereby making them available to the host organisms. Siderophore producing bacteria was isolated from the rhizospheric soil of Eragrostis cynosuroides by CAS agar screening and CAS-shuttle assay method. Among five positive isolates, DR2 produced a relatively high level of siderophore (69.81 SU%) and was identified as catecholate type. Further, it was identified as Bacillus subtilis DR2 (KP455653) based on 16S rRNA gene sequencing and phylogenetic analysis. Media optimization revealed that the strain B. subtilis DR2 showed maximum siderophore yield (80.60 SU%) under optimized condition of 72 h incubation at 35 °C in succinate media at pH 8, supplemented with sucrose as carbon and NaNO3 as nitrogen sources. It was further tested as seed inoculants under pot culture conditions and was found to be very efficient in seed germination and growth promotion of Coriandrum sativum. Thus, the present study signifies that B. subtilis DR2 may be a promising candidate with potential of plant growth promotion to be used as biofertilizer for various crops.

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