Functional expression and synergistic cooperation of xylan‐degrading enzymes from Hypocrea orientalis and Aspergillus niger

Abstract

AbstractBACKGROUNDXylan plays an important role in the enzymatic digestion of biomass, but xylan‐degrading enzymes are expensive to produce. Current research is focused on improving the activity and efficacy of hydrolytic enzymes by molecular engineering and on understanding the synergistic cooperation of these enzymes.RESULTSIn this study, xylan‐degrading enzymes, including endo‐β‐1,4‐xylanases (HoXyn11A and AnXyn10C), β‐xylosidases (AnXln3D) and α‐L‐arabinofuranosidases (AnAxh62A) from Hypocrea orientalis and Aspergillus niger, were expressed at high levels in Pichia pastoris. Substrate specificity and end product analysis verified the mode of actions of the recombinant enzymes, which were specific for xylan degradation. Synergistic cooperation among these recombinant enzymes was clearly demonstrated. AnXyn10C was more efficient than HoXyn11A for producing both xylose and xylo‐oligosaccharides from beechwood xylan and wheat arabinoxylan. AnAxh62A displayed better cooperative effects with HoXyn11A than AnXyn10C in the hydrolysis of wheat arabinoxylan and increased the yield of xylobiose and xylotriose 8.6‐fold and 7.3‐fold, respectively. Although AnXln3D was the key enzyme for producing xylose, the yield of xylose depended strongly on the main‐chain and side‐group cleaving enzymes.CONCLUSIONThis study will facilitate the development of highly efficient enzyme cocktails for the bioconversion of lignocellulosic biomass into monosaccharides and xylo‐oligosaccharides. © 2014 Society of Chemical Industry