Efficient function and characterization of GH10 xylanase (Xyl10g) from Gloeophyllum trabeum in lignocellulose degradation

The xylanase gene from Gloeophyllum trabeum was cloned and expressed in Pichia pastoris GS115. Xyl10g has a molecular weight of approximately 50 kDa, and exhibits maximum specific activity at 70 °C and a broad range of pH 4.0-7.0. Purified recombinant Xyl10g efficiently degraded popping-pretreated corn stover and newspaper waste at 50 °C and pH 4.0 after 24 h, and showed synergistic effects with Cel5B (endoglucanase) and BglB (β-glucosidase) to increase reduced sugar levels by about 1.71- to 1.88-fold and 2.26- to 2.48-fold, respectively. Although Xyl10g has low specific activity for beechwood xylan, as compared to XynA, Xyl10g more efficiently degraded corn stover than did XynA. According to immunogold labeling analysis, Xyl10g can attack highly substituted, unsubstituted, and low-substituted xylans, whereas XynA cannot efficiently attack highly substituted xylans, which is important for lignocellulose degradation. These results suggest that GH10 Xyl10g can be used for lignocellulose degradation.