PRODUCTION OF ETHANOL BY THE THERMOTOLERANT YEAST KLUYVEROMYCES-MARXIANUS IMB3 DURING GROWTH ON LACTOSE-CONTAINING MEDIA

The thermotolerant yeast strain, Kluyveromyces marxianus IMB3 was shown to be capable of growth and ethanol production on lactose containing media at 45 degrees C. On media containing 4% (w/v) lactose, ethanol production increased to 6.0g/l within 50h and this represented 29% of theoretical yield. During growth on lactose containing media the organism was shown to produce a cell-associated beta-galactosidase and no significant enzyme could be detected in the extracellular culture filtrate. Addition of beta-galactosidase, released from Kluyveromyces marxianus IMB3 cells, to active fermentations, resulted in increasing ethanol production to 53% of theoretical yield at 45 degrees C.