Growth and metabolite formation were studied as a function of oxygen feed rate, in glucose-limited chemostat cultures of Hanseniaspora uvarum K-5 at a dilution rate of 0.26 h(-1). Alcoholic fermentation occured at an oxygen feed rate of 80 mmol.l(-1).h(-1). Below this value, pyruvate decarboxylase and alcohol dehydrogenase were present at high levels. In contrast, activities of oxidative metabolism enzymes, pyruvate dehydrogenase, aldehyde dehydrogenase and acetyl-CoA synthetase, decreased.