Abstract
Of the yeasts that ferment D-glucose anaerobically, over 40% can use certain glycosides and D-galactose oxidatively, but cannot ferment them. This phenomenon is here called the Kluyver effect. More than half the yeast species described which exhibit this effect do so with more than 1 substrate. Yeasts showing the effect with maltose, cellobiose and D-galactose were compared with fermenting strains, to determine whether enzyme inactivation or cessation of sugar uptake was responsible. The different responses of the yeasts to anaerobic conditions, with respect to their enzymic activity, sugar uptake and CO2 production, consistently showed that the Kluyver effect resulted from the requirement of transport for O2, and this seems to be the common explanation throughout the yeasts.