THE EFFECTS OF MN2+ ON ETHANOL-PRODUCTION BY KLUYVEROMYCES-MARXIANUS IMB3 DURING GROWTH ON LACTOSE-CONTAINING MEDIA AT 45-DEGREES-C

It has previously been demonstrated that the thermotolerant yeast strain, K. marxianus IMB3 is capable of growth and ethanol production on lactose containing media at 45 degrees C. Although the organism is capable of producing a beta-galactosidase, that enzyme has been shown to be extremely thermolabile at 45 degrees C and this has been reflected in reduced efficiencies with respect to conversion of lactose to ethanol. In this paper we demonstrate that addition of Mn2+ ions to enzyme preparations contributes significantly to enzyme stability at 45 degrees C. We also demonstrate that addition of Mn2+ to fermentations results in increased efficiency of conversion of lactose to ethanol at this temperature.