Growth behaviour and IAA production by a Rhizobium sp. isolated from root nodules of a leguminous medicinal herb, Dolichos biflorus. L., in culture

Abstract

A Rhizobium sp. isolated from the root nodules of a leguminous medicinal herb Dolichos biflorus. L., was found to produce large amounts of indole acetic acid (IAA) (139.1 μg/ml) from L-tryptophan supplemented basal medium. The Rhizobium sp. was a fast growing species which reached its stationary phase of growth and IAA production at 24 h. An enrichment of the carbon — free incubation medium with sucrose (1%), cytokinin (20 μg/ml) and KNO 3 (0.2%) promoted the IAA production by 424.38% over control. The possible role of the rhizobial production of IAA on the rhizobia — legume symbiosis is discussed.