Induction of the xylitol dehydrogenase of Pullularia pullulans

Abstract

Pullularia pullulans, a yeastlike fungus, metabolizes xylitol via an intracellular xylitol dehydrogenase. Formation of the enzyme was induced by D-xylose and inhibited by cycloheximide, suggesting de novo synthesis. The induction study was carried out with noninduced cells of P. pullulans harvested from a glycerol medium. The cells initiated synthesis of xylitol dehydrogenase without a detectable lag phase when 1.5% xylose was added. The differential rate of xylitol dehydrogenase synthesis was 1.4 units per mg of synthesized protein. Kinetic studies of enzyme induction in a growing culture showed that the highest level of specific activity was reached at 25 to 27 h of growth, with an increase of 200 times over the basal level in the glycerol medium.