Effect of pretreatment methods on the synergism of cellulase and xylanase during the hydrolysis of bagasse

The effect of pretreatment with peracetic acid (PAA) or an ionic liquid (1-ethyl-3-methylimidazolium acetate, [Emim][OAc]) on the synergism between endoglucanase and endoxylanase in the hydrolysis of bagasse was investigated. An endoglucanase, Cel6A, with a carbohydrate-binding module (CBM) and two endoxylanases, XynZ-C without a CBM and Xyn11A with an intrinsic xylan/cellulose binding module (XBM), were selected. The hemicellulose content, especially arabinan, and the cellulose crystallinity of bagasse were found to affect the cellulase-xylanase synergism. More specifically, higher synergism (above 3.4) was observed for glucan conversion, at low levels of arabinan (0.9%), during the hydrolysis of PAA pretreated bagasse. In contrast, [Emim][OAc] pretreated bagasse, showed lower cellulose crystallinity and achieved higher synergism (over 1.9) for xylan conversion. Ultimately, the combination of Cel6A and Xyn11A resulted in higher synergism for glucan conversion than the combination of Cel6A with XynZ-C, indicating the importance of the molecular architecture of enzymes for metabolic synergism. (C) 2015 Elsevier Ltd. All rights reserved.