Characterization, immobilization, and activity enhancement of cellulase treated with supercritical CO2

Enzyme activity enhancement represents a great opportunity for biotechnological production, while recovery of most enzymes from media, possible loss of catalytic activity in reactions, and denaturation occur. In this study, the activity and stability enhancement, kinetic parameters, and thermal inactivation for cellulose hydrolysis of supercritical carbon dioxide (SC-CO2)-treated and untreated cellulase from Trichoderma longibrachiatum as a model enzyme are presented, and the activity enhancement capability of SC-CO2 for cellulase after consecutive enzymatic reactions is discussed. The pH and temperature stability were pH 5 and 50 A degrees C for the enzymatic reaction, whereas the kinetic parameter values, V (max) and K (m), were calculated using the Michaelis-Menten model. The optimal operational parameters were determined to be 54 A degrees C, 180 bar, and 10 g/min CO2 flow rate for 120 min, yielding 48.3 % higher activity (9.27 mu mol/ml/min) than for untreated enzyme. In addition, SC-CO2-treated cellulase with the highest activity was immobilized on NaY zeolite, and consecutive reactions were carried out. The presented results suggest that enzymes as catalysts in biochemical applications can be improved by using supercritical fluids as potential media.