PRODUCTION OF EXTRACELLULAR POLYSACCHARIDES BY A RHIZOBIUM SPECIES FROM THE ROOT-NODULES OF TEPHROSIA-PURPUREA PERS

The Rhizobium sp., isolated from the root nodules of the leguminous cl imbing herb, Tephrosia Purpurea Pers., produced high amounts of extrac ellular polysaccharides (EPS) in yeast extract mannitol medium. Growth and EPS production started simultaneously, but the production reached its maximum in the stationary growth phase of the bacteria. Attempts were made to optimize the cultural requirements for growth and maximum EPS production. The EPS production was increased by 72.5% over the co ntrol when the medium was supplemented with mannitol (2%), thiamine hy drochloride (5 mu g/ml) and KNO3 (0.1%). The EPS contained glucose, ga lactose and mannose monomers. The possible role of the rhizobial EPS w as discussed.