An inducible D-arabitol dehydrogenase from Aerobacter aerogenes.

A capsulated strain of derobacter aerogenes 1033 (2) has been found to metabolize glycerol via two separate pathways. The first pathway was mediated by a diphosphopyridine nucleotidelinked glycerol dehydrogenase and a specific dihydroxyacetone kinase, whereas the second pathway involved a specific glycerol kinase and a DPN-independent L-a-glycerophosphate dehydrogenase (3-5). Although all the above enzymes were inducible by glycerol, their relative levels in cells growing on glycerol as the sole source of energy and carbon were modulated by oxygen tension of the media (4). Thus, vigorous oxygenation of growing cultures increased the level of glycerol kinase but greatly depressed the levels of the glycerol dehydrogenase and dihydroxyacetone kinase. Anaerobiosis, which would render the DPNindependent L-cr-glycerophosphate dehydrogenase inoperative, greatly elevated the two enzymes in the glycerol dehydrogenase pathway. During the course of this study, a similar effect of oxygen on the inducible level of another DPN-linked dehydrogenase was found in this organism. This enzyme converted n-arabitol to D-xylulose and n-mannitol to n-fructose. The stereospecificity and the physiological role of this enzyme will be discussed in the present communication.