EFFECT OF GLUCOSE ON PYRUVATE UTILIZATION BY RHODOTORULA GLUTINIS

The utilization of glucose and pyruvate by the yeast Rhodotorula glutinis in a medium containing both carbon sources has been studied. Glucose is readily consumed whereas the uptake of pyruvate is completely blocked by the presence of the sugar. The content of pyruvate kinase and phosphoenolpyruvate carboxykinase in R. glutinis cells growing on glucose plus pyruvate are drastically affected with time by the disappearance of the sugar from the culture medium. After complete exhaustion of glucose, the level of pyruvate kinase drops sharply down to a minimum whereas that of phosphoenolpyruvate carboxykinase rises abruptly up to a maximum. Feeding experiments with labelled compounds show that glucose affects the utilization of the amino acids alanine and aspartate, and conversely that the amino acids influence the utilization of the sugar. Glucose breakdown and its incorporation into polysaccharides is controlled by the amino acids and gluconeogenesis from the amino acids is controlled by the sugar. © 1969 Springer-Verlag.