Autonomous metabolic oscillation in continuous culture of Saccharomyces cerevisiae grown on ethanol.

When the yeast Saccharomyces cerevisiae was grown under aerobic continuous culture conditions with a medium containing ethanol as carbon source, an autonomous sustained metabolic oscillation appeared. This oscillation was observed in rates and concentrations of various parameters such as, ethanol, oxygen uptake rate, carbon dioxide evolution rate, NaOH addition rate for pH control, acetate, and intracellular pH. No changes were observed in concentrations of stock carbohydrates. Intracellular pH changes were out of phase with oxygen uptake rate, which was reverse of the results with glucose-based oscillation. These results suggested that changes in glycolytic flux and intracellular pH were not regulating the oscillation. Analysis suggested that one of the oscillatory regulation points was located in the ethanol assimilation pathway.