Role of hemicellulases in production of fermentable sugars from corn stover

In this work, the roles of hemicellulases, endoxylanase and beta-xylosidase, in improving the hydrolysis of corn stover pretreated by aqueous ammonia (CS-AA) and dilute acid (CS-DA) were evaluated. Synergistic actions of endoxylanase and beta-xylosidase were observed in the release of xylose in the hydrolysis of both isolated xylan and xylan in pretreated corn stover. Endoxylanase significantly reduced the negative effect of xylan on the action of cellulases, especially on cellobiohydrolase I. The addition of beta-xylosidase from Selenomonas ruminantium increased the xylose yields from 9.6% and 13.0% to 31.7% and 47.6% in the hydrolysis of CS-AA by cellulases and xylanase at 40 degrees C and 50 degrees C, respectively. Furthermore, the addition of thermostable beta-xylosidase from Entamoeba coli increased glucose yields from 40.3% and 20.7% to 44.0% and 26.6% in the hydrolysis of CS-AA and CS-DA by cellulases and xylanase at 50 degrees C, respectively. beta-xylosidase significantly reduced xylo-oligosaccharides inhibition on cellobiohydrolase I by converting most of xylo-oligosaccharides (93.6%) to the less inhibitory xylose, showing the importance and potential benefits of beta-xylosidase in efficient and complete hydrolysis of lignocelluloses. (C) 2015 Elsevier B.V. All rights reserved.