Changes in Glucose 6-Phosphate and Storage Carbohydrates during Catabolite Derepression in Saccharomyces cerevisiae

Changes in the cellular content of glucose 6-phosphate and storage carbohydrates during catabolite derepression were measured during the diauxic growth of Saccharomyces cerevisiae on glucose (1 %, w/v) medium. After the exhaustion of glucose there were transient increases in glucose 6-phosphate, alkali-soluble glycogen and trehalose, reflecting enhanced gluconeogenesis, followed by an increase in acid-soluble glycogen. During the subsequent adaptation to growth on ethanol the amounts of glucose 6-phosphate, trehalose and glycogen returned to basal levels. Thus storage carbohydrates, of which glycogen is quantitatively the most important, appear to act as the energy source for catabolite derepression.