Short communication: Ethanol production from cellulose at 45°C using a batch-fed system containing alginate-immobilized Kluyveromyces marxianus IMB3

The thermotolerant yeast, Kluyveromyces marxianus IMB3, was grown in batch culture at 45°C on cellulose-containing media, supplemented with exogenous cellulase activity. At various stages during fermentation, both substrate and enzyme were added in batch mode and fermentation was continued for 220 h. Ethanol production increased to 20 g/l at 200 h, representing 45% of the maximum theoretical yield. In subsequent experiments, the organism was immobilized in calcium alginate beads and these were used in a similar, batch-fed system at 45°C. Again, fermentation was continued for 220 h and ethanol production increased to its maximum, of 28 g/l, within 100 h and this represented in excess of 60% of the maximum theoretical yield.