Production of Indole-3-Acetic Acid by Rhizobium Isolates from Sesbania Species

Rhizobium strains isolated from root (Sesbania procumbens) and stem nodules (S. rostrata and S. procumbens) of Sesbania species were tested for their ability to produce Indole-3-Acetic Acid (IAA). The isolates produced maximum amount of IAA in culture after 72 h of incubation and at 3.0 mg mL 1 L-tryptophan concentration. The effect of different carbon and nitrogen sources on IAA production was also studied and it revealed that, glucose (1%) and potassium nitrate (0.1%) were found to be best promoters for IAA production. An addition of EDTA (0.1 g mL 1) significantly increased the IAA production over controls and the production was maximum at 0.2 g mL 1 EDTA concentration. Among the three isolates, maximum amount of IAA was produced by Rhizobium isolate from stem nodule of S. procumbens. The IAA was extracted, purified and identified by thin layer chromatography.