▎ 摘　　要

Cellulase enzyme was purified from a psychrophilic strain of Bacillus subtilis obtained from east Himalayan mountains. The native enzyme showed optimum activity at 15 degrees C and pH 8.0.The Magnesium oxide nanoparticle (MgN) supplemented enzyme when immobilized on graphene oxide nanosupport (GO), via glutaraldehyde as cross linker, showed 2.98 folds increase in enzymatic activity at 8 degrees C and more than 3.5 folds activity increment at 90 degrees C. The MgN-cel on graphene (GO-MgN-cel) showed a decrease in K-m. by 6.7 folds at 8 degrees C and 34 folds at 90 degrees C. GO-MgN-cel showed 5 fold and 4.7 fold increase in V-max at 8 degrees C and 90 degrees C respectively than the untreated enzyme.When compared to native enzyme, GO-MgN-cel had t(1/2) (half life) and E-d increased by 72.5 fold and 2.48 fold respectively at 90 degrees C; and 41.6 fold and 2.19 fold respectively at 8 degrees C. Enzymatic activity of GO-MgN-cel was retained even after 12 repeated uses and showed storage stability at 4 degrees C for more than 120 days. This nanoparticle assisted immobilization technique can be utilized in bioprocessing industries which require functioning at these extreme ranges of temperature. (C) 2016 Elsevier Inc. All rights reserved.