Metabolic responses of Saccharomyces cerevisiae CBS 8066 and Candida utilis CBS 621 upon transition from glucose limitation to glucose excess

Abstract

When chemostat cultures of Saccharomyces cerevisiae CBS 8066 and Candida utilis CBS 621, grown under glucose limitation, were pulsed with excess glucose, both organisms initially exhibites similar rates of glucose and oxygen consumption. However, striking differences were apparent between the two yeasts with respect to the production of cell mass in the culture and metabolic excretion. Upon transition from glucose limitation excess, S. cerevisiae produced much ethanol but growth rate close to that under glucose limitation. C. utilis, on the other hand, produced little ethanol and immediately started to accumulated cell mass at a high rate. This high production rate of protein synthesis. Upon a glucose pulse both yeasts excreated pyuvate. In contrast to C. utilis. S. cerevisiae also excerted various tricarboxylic acid cycle intermediates, both under steady‐state conditions and after exposure to glucose excess, These results and those of theoritical calculations on ATP flows support the hypothesis that the ethanol production as a consequences of pyruvate accumulatiion in S. cerevisiae, occuring transition from glucose limitaion to glucose excess, is caused by a limited capacity of assimilatory pathways.