LOW-MOLECULAR-WEIGHT THERMOSTABLE BETA-D-GLUCOSIDASE FROM ACIDOTHERMUS-CELLULOLYTICUS

Industrial use of cellulase enzymes, including beta-D-glucosidases, ca n be greatly improved and expanded by the discovery and characterizati on of more robust, thermotolerant enzymes. A new thermostable beta-D-g lucosidase was isolated from Acidothermus cellulolyticus culture broth . This enzyme has a molecular weight of 52.5 kDa, an isoelectric pI of 4.1, and a pH activity optimum of 4.5. The optimum temperature for ac tivity on p-nitrophenyl-beta-D-glucoside is 63 degrees C. This value i s approximately 20 degrees C higher than temperature optima displayed by most previously characterized beta-D-glucosidases.