GROWTH-BEHAVIOR AND IAA PRODUCTION BY A RHIZOBIUM SP ISOLATED FROM ROOT-NODULES OF A LEGUMINOUS MEDICINAL HERB, TEPHROSEA-PURPUREA PERS, INCULTURE

The Rhizobium sp. isolated from the root nodules of a leguminous medic inal herb, Tephrosea purpurea produced a high amount of indole acetic (126 mu g/ml) from L-tryptophan supplemented basal medium. Growth and indole acetic acid production started simultaneously, the bacteria had a separate growth and production phase. The production was maximum in the stationary phase of growth of the bacteria. Attempts were made to optimize the cultural requirements for the growth and maximal IAA pro duction. The IAA production by the Rhizobium sp, was increased by 487. 5% when the medium was supplemented with sucrose (1%), NiCl2, 6 H2O (2 mu g/ml), nicotinic acid (1.5 mu g/ml), cetyl pyridium chloride (1 mu g/ml) and KNO3 (0.2%). The possible role of the rhizobial production of indole acetic acid on the Rhizobium - legume symbiosis is discussed .