Bioproduction of Indole Acetic Acid by Rhizobium Strains Isolated from Root Nodules of Green Manure Crop, Sesbania sesban (L.) Merr.

Twenty six Rhizobium strains were isolated from root nodules of Sesbania sesban (L.) Merr. collected from different regions of Andhra Pradesh. All the 26 Rhizobium strains produced indole acetic acid (IAA), but maximum amount was produced by only five strains in yeast extract mannitol  (YEM) medium supplemented with L-tryptophan. The strains were found to elaborate maximum IAA when fed with 2.5 mg/ml L-tryptophan. Cultural requirements were optimized for maximum growth and IAA production. The strains differ in their growth and production of IAA on different carbon and nitrogen sources. Addition of cell wall affecting agents increased the IAA production over controls. The compound was extracted, purified and structurally confirmed as IAA.