The effect of aerobic metabolism on the inducible glycerol dehydrogenase of Aerobacter aerogenes.

Aerobacter aerogenes strain 1033 can utilize glycerol as sole source of carbon and energy under aerobic and anaerobic conditions (2). With the aid of isotope enantiomorphs of glycerol1-V it could be shown that an important pathway of glycerol metabolism in this organism involves dihydroxyacetone as an intermediate between glycerol and pyruvate (3). The validity of this conclusion was strengthened by the demonstration that extracts of this organism contain an inducible diphosphopyridine nucleotide-linked glycerol dehydrogenase (3, 4). Further support comes from the finding, reported here, that these extracts contain also an inducible specific dihydroxyacetone kinase. However, as will be shown, this pathway of glycerol metabolism can be used by the cell only under relatively anaerobic conditions. Under strongly aerobic conditions glycerol is apparently metabolized by a pathway identical with the one previously discovered in another organism, Aerobacter aerogenes strain 1041 (2, 3): conversion to L-a-glycerophosphate, followed by the oxidation of this compound to triose phosphate. The failure of the cell, under aerobic conditions, to metabolize glycerol through dihydroxyacetone seems to be explained by an unexpected property of the diphosphopyridine nucleotide-linked glycerol dehydrogenase: this enzyme is rapidly destroyed in the intact cell engaged in aerobic metabolism.