Dilution rate (1/h) was calculated as a flow rate divided by the working volume of the column. The working volume of the column was determined by pumping known volume of water from the bot- tom to the top. The overall ethanol productivity in grams per liter per hour during continuous cultivation of ethanol producing S. cerevisiae was expressed as grams per liter of total ethanol multi- plied by dilution rate (1/h). Ethanol yield (g/g) was calculated by dividing ethanol (g/l) by utilized reducing sugar (g/l).