Abstract

An investigation was carried out on the growth and ethanol production of a novel thermotolerant ethanol-producing Kluyveromyces marxianus IMB3 yeast strain. It grew aerobically on glucose, lactose, cellobiose, xylose and whey permeate and fermented all the above carbon sources to ethanol at 45 degrees C. This strain was capable of growing under anaerobic chemostat fermentation conditions at 45 degrees C and a dilution rate of 0.15 h(-1) and produced less than or equal to 0.9 g/l biomass and 1.8% (v/v) ethanol. An increase in biomass (up to 10.0 g/l) and ethanol (up to 4.3% v/v at 45 degrees C and 7.7% v/v at 40 degrees C) were achieved by applying a continuous two-stage fermentation in sequence (one aerobic and one anaerobic stage) or a two-stage anaerobic fermentation with cell recycling. Potential applications, involving alcohol production systems, for use in dairy and wood related industries, were discussed.