UNCOUPLED GLYCEROL DISTRIBUTION AS THE ORIGIN OF THE ACCUMULATION OF 3-HYDROXYPROPIONALDEHYDE DURING THE FERMENTATION OF GLYCEROL BY ENTEROBACTER-AGGLOMERANS CNCM-1210

Batch fermentation of glycerol to 1,3-propanediol (1,3PPD) by Enteroba cter agglomerans CNCM 1210 showed the lethal accumulation of 3-hydroxy propionaldehyde (3-HPA) when performed under initial substrate content higher than 40 g/L. Assigned to the inhibition by the NAD/NADH ratio of the 3-HPA converting enzyme: 1,3PPD dehydrogenase, intracellular as says were conducted in an attempt to identify the metabolic mechanisms involved in the increase of that ratio. An overflow metabolism throug h the 1,3PPD formation pathway was established, while a catabolic limi tation in the oxidative branch at the level of glyceraldehyde-3-phosph ate dehydrogenase occurred. Uncoupled activities of synthesis and cons umption of reducing equivalents are thus suspected to provoke the incr ease of the NAD/NADH ratio and the subsequent accumulation of 3-HPA. ( C) 1998 John Wiley & Sons, Inc.