GLYCEROL CONVERSION TO 1,3-PROPANEDIOL BY CLOSTRIDIUM-PASTEURIANUM - CLONING AND EXPRESSION OF THE GENE ENCODING 1,3-PROPANEDIOL DEHYDROGENASE

When grown on glycerol as sole carbon and energy source, cell extracts of Clostridium pasteurianum exhibited activities of glycerol dehydrog enase, dihydroxyacetone kinase, glycerol dehydratase and 1,3-propanedi ol dehydrogenase. The genes encoding the latter two enzymes were clone d by colony hybridization using the dhaT gene of Citrobacter freundii as heterologous DNA probe and expressed in Escherichia coli. The nativ e molecular mass of 1,3-propanediol dehydrogenase (DhaT) is 440 000 Da . The dhaT gene of C. pasteurianum was subcloned and its nucleotide se quence (1158 bp) was determined. The deduced gene product (41 776 Dal revealed high similarity to DhaT of C. freundii (80.5% identity; 89.8% similarity).