[Effect of 2-ketogluconic acid synthesis on the exopolysaccharide production in a Rhizobium meliloti strain].

Two categories of carbon substrates are defined for Rhizobium meliloti: the first favours the synthesis of exopolysaccharides (fructose belongs to this category) while the other is not suitable (glucose belongs to this category). With fructose, resting cells synthesize polysaccharides during more than 100 h and this synthesis is at its best in aerobic conditions at 30 degrees C. With glucose, 2-ketogluconic acid accumulates and rapidly stops the synthesis. The method used to stop this acidification allows with glucose a synthesis which can be compared to the one obtained with fructose.