EFFECT OF GLUCOSE ON GLYCEROL METABOLISM BY CLOSTRIDIUM-BUTYRICUM DSM-5431

The levels of 1,3-propanediol dehydrogenase and of the glycerol dehydr ogenase in Clostridium butyricum grown on glucose-glycerol mixtures we re similar to those found in extracts of cells grown on glycerol alone , which can explain the simultaneous glucose-glycerol consumption. On glycerol, 43% of glycerol was oxidized to organic acids to obtain ener gy for growth and 57% to produce 1,3-propanediol. With glucose-glycero l mixtures, glucose catabolism was used by the cells to produce energy through the acetate-butyrate production and NADH, whereas glycerol wa s used chiefly in the utilization of the reducing power since 92-93% o f the glycerol flow was converted through the 1,3-propanediol pathway. The apparent K(m)s for the glycerol dehydrogenase was 16-fold higher for the glycerol than that for the glyceraldehyde in the case of the g lyceraldehyde-3-phosphate dehydrogenase and fourfold higher for the NA D(+), providing an explanation for the shift of the glycerol flow towa rd 1,3-propanediol when cells were grown on glucose-glycerol mixtures.