Swollenin aids in the amorphogenesis step during the enzymatic hydrolysis of pretreated biomass

A key limitation in the overall hydrolysis process is the restricted access that the hydrolytic enzymes have due to the macro-and-micro structure of cellulose and its association with hemicellulose and lignin. Previous work has shown that several non-hydrolytic proteins can disrupt cellulose structure and boost the activity of hydrolytic enzymes when purer forms of cellulose are used. In the work reported here, Swollenin primarily disrupted the hemicellulosic fraction of pretreated corn stover, resulting in the solubilisation of monomeric and oligomeric sugars. Although Swollenin showed little synergism when combined with the cellulase monocomponents exoglucanase (CEL7A) and endoglucanase (CEL5A), it showed pronounced synergism with xylanase monocomponents Xylanase GH10 and Xylanase GH11, resulting in the release of significantly more xylose (>300%). It appears that Swollenin plays a role in amorphogenesis and that its primary action is enhancing access to the hemicellulose fraction that limits or masks accessibility to the cellulose component of lignocellulosic substrates. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.