Isolation and characterization of Bacillus species for the detection of siderophores

Bacillus subtilis group produces a variety of secondary metabolites in which siderophores are lower molecular weight iron chelating compounds produced to overcome iron deficient environments and aid the delivery of iron inside the bacterial cell for numerous metabolic activities The present study aims to isolate and evaluate Bacillus species from fermented soybean food and soil samples for the detection of siderophores. A total of 20 samples including soil (11) and fermented soybean food (9) were processed by serial dilution and the Bacillus species isolated. Morphological testing, biochemical testing and 16S rRNA gene sequencing were performed to confirm the phenotype and genotype of the isolates. Two media such as Luria Bertani (LB) and iron-deficient succinate media (IDSM), were utilized for siderophores production by qualitative and quantitative measures using the Chrome Azurol Sulfonate (CAS) assay. Using phenotypic and genotypic characterization techniques, 26 Bacillus species were isolated from 20 samples. Based on phenotypic and genotypic methods, among 20 samples, 26 Bacillus isolates were identified. The supernatant of all the isolates in LB broth was positive whereas IDSM was negative qualitatively. However, in quantitative analysis, both LB and IDSM demonstrated the yield of siderophores. Thus, the study concludes that Bacillus species producing siderophores can be promising candidates with wide applications in pharmaceutical and environmental studies.