The effect of glucose on polyol metabolism by Rhizobium trifoiji was studied. Phenomena similar to catabolite repression and catabolite inhibition were observed. The catabolism of glucose to at least glucose 6-phosphate was required for the effects to be exerted. The pathways used by Rhizobium for carbohydrate catabolism have been studied by several workers. The Entner-Doudoroff pathway is thought to be the major pathway used for hexose catabolism in both fast-and slow-growing rhizobia (2, 3, 6, 9, 10), whereas the nonoxidative