STUDIES ON THE ROOT-NODULES OF LEGUMINOUS PLANTS - THE PRODUCTION OF INDOLE ACETIC-ACID IN CULTURE BY A RHIZOBIUM SP FROM A LEGUMINOUS CLIMBING SHRUB DERRIS SCANDENS BENTH

The Rhizobium sp. when isolated from the root nodules of a leguminous climbing shrub Derris scandens produced a high amount of indole acetic acid (IAA) (135.2 mu g/ml) from the tryptophan-supplemented basal med ium. Growth and IAA production started simultaneously, and the maximum amount of IAA was produced as a secondary metabolite in the stationar y phase of growth. The IAA production by the Rhizobium sp. was increas ed by 503% when the medium was supplemented with mannitol (2%), KNO3 ( 0.2%), nicotinic acid (0.1 mu g/ml) and MnSO4 (1 mu g/ml) in addition to tryptophan (4 mg/ml). The possible role of the rhizobial production of IAA on the rhizobia-legume symbiosis is also discussed.