Improving the Hydrolytic Action of Cellulases by Tween 80: Offsetting the Lost Activity of Cellobiohydrolase Cel7A

Abstract

Deactivation of cellulase components has been shown to play a key role in restricting the efficient conversion of biomass to fermentable sugars and other chemicals. A potential strategy to increase the cellulases’ hydrolytic efficiency could be the development of cost-effective technologies to offset the easily inactivated components in commercial cellulase preparations. In this work, a potential strategy to address this issue is reported. During the hydrolysis of Avicel and aqueous ammonia-pretreated corn stover and spruce, the deactivation of cellobiohydrolase was found to be the primary reason for the loss of total cellulase activities. Kinetic data indicated that Tween 80 was a specific activator of cellobiohydrolase, but not of endoglucanase and β-glucosidase. The activation effect of Tween 80 showed a specific positive role in suppressing inhibition of cellobiohydrolase by lignin, hemicelluloses, and their derivatives and thus maintained the enzyme in high activity during the enzymatic hydrolysis process. When cellobiohydrolase was supplemented with a mixture of these inhibitors (0.5 mg mL–1 lignin, 0.5 mg mL–1 hemicelluloses, and 0.5 mmol L–1 hemicellulose oligomers), 60% of the original cellobiohydrolase activity was lost, while approximately 40% of the lost activity was restored by Tween 80. These results are expected to be significant for future research concerning the beneficial action of surfactants, improvement of cellulase activities, and recycling of enzymes during the industrial cellulose conversion process.