Regulation of Glycerol Catabolism in Klebsiella aerogenes

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Abstract
The utilization of glycerol as a carbon source for growth by Klebsiella aerogenes, strain 2103, involves separate aerobic (sn-glycerol-3-phosphate or G3P) and anaerobic (dihydroxyacetone or DHA) pathways of catabolism. Enzyme and transport activities of the aerobic pathway are elevated in cells grown under oxygenated conditions on glycerol or G3P. Anaerobic growth on G3P as carbon source requires the presence of an exogenous hydrogen acceptor such as fumarate; cells thus grown also are highly induced in the G3P pathway. Anaerobic growth on glycerol requires no exogenous hydrogen acceptors; cells thus grown are highly induced in the DHA pathway but almost uninduced in the G3P pathway and the addition of fumarate electron acceptors has no effect on the relative levels of the two pathways. When both glycerol and G3P are provided anaerobically with fumarate, the DHA pathway is still preferentially induced, which probably accounts for the exclusive utilization of glycerol until its exhaustion. These observations suggest the presence of a regulatory control of G3P pathway imposed by the operation of the DHA pathway.