PARTIAL CHARACTERIZATION OF BETA-GLUCOSIDASE ACTIVITY PRODUCED BY KLUYVEROMYCES-MARXIANUS IMB3 DURING GROWTH ON CELLOBIOSE-CONTAINING MEDIAAT 45-DEGREES-C

We report- the partial characterization of a beta-glucosidase produced during growth of the thermotolerant yeast, K. marxianus IMB3 on lacto se-containing media at 45 degrees C. The enzyme had Km values of 1.1 m M and 14.8 mM, for the substrates p-nitrophenyl-beta-D-glucoside and c ellobiose, respectively. The enzyme had a pH optimum of 5.5 and was op timally active at 50 degrees C. It was stable up to 125 hours at 25 de grees C and 35 degrees, with half-lives of 45 hours and 2 hours at 45 degrees C and 50 degrees C, respectively. inactivated by Hg2+. Ethanol concentrations [1-10% (v/v)] had little effect an activity. Glucose ( 20 mM) caused inhibition when p-nitrophenyl-beta-D-glucoside was used as substrate, whereas lactose at similar concentrations had no effect.