Effect of glucose on glycerol metabolism by Clostridium butyricum DSM 5431.

The levels of 1,3-propanediol dehydrogenase and of the glycerol dehydrogenase in Clostridium butyricum grown on glucose-glycerol mixtures were 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 energy for growth and 57% to produce 1,3-propanediol. With glucose-glycerol mixtures, glucose catabolism was used by the cells to produce energy through the acetate-butyrate production and NADH, whereas glycerol was used chiefly in the utilization of the reducing power since 92-93% of 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 glyceraldehyde-3-phosphate dehydrogenase and fourfold higher for the NAD+, providing an explanation for the shift of the glycerol flow toward 1,3-propanediol when cells were grown on glucose-glycerol mixtures.