A deeper investigation on carbohydrate cycling in Sinorhizobium meliloti

Recycling of triose-phospate and pentose-phosphate was previously reported on glucose in Sinorhizobium meliloti, a polysaccharide-synthesizing bacteri um, but the metabolic basis of such processes remained unclear. In this wor k, we have used C-13-labelling strategies to demonstrate that carbohydrate cycling in this organism is independent of the gluconate bypass, the altern ative pathway for glucose assimilation involving its periplasmic oxidation into gluconate. Furthermore, carbohydrate cycling in S. meliloti is also ob served on fructose, making the situation in this bacterium significantly di fferent from that depicted for alginate-synthesizing species. (C) 2001 Fede ration of European Biochemical Societies, Published by Elsevier Science B.V . All rights reserved.