Coenzyme B12-Dependent Glycerol Dehydratase Deficiency in Klebsiella pneumoniae

The physiology and fermentation properties of coenzyme B-12-dependent glycerol dehydratase deficient mutant Klebsiella pneumoniae B1.9131 were investigated. Compared with that of wild type strain, glycerol dehydratase activity decreased by 80 %. Activities of dha regulon coded two enzymes are influenced by inactivation of GDHt. 1,3-Propanediol oxidoreductase activity decreased by 62 % while glycerol dehydrogenase activity increased by 36 %. Fed-batch fermentation showed that more of the metabolic flux of glycerol was directed to lactate and ethanol in the mutant. Instead, lactate other than 1,3-propanediol was the main product and its final concentration increased from 41 to 76 g L-1 with mutant isolate. The concentration of 1,3-propanediol decreased from 91 to 40 g L-1. The results demonstrate that GDHt is not indispensable in glycerol metabolism but is crucial for the efficient synthesis of 1,3-propanediol.