For some time, lactose in whey has been recognized as an ideal substrate for the production of both fuel and potable ethanol via fermentation. ’ Efficient conversion and process design have been hindered by the facts that the concentra- tion of lactose in whey is relatively low and that relatively few fermenting yeasts are capable of lactose utilization. The most common alternatives to using conventional strains of Saccharomyces cerevisiae together with exogenously added