Biochemical characterization of an engineered bifunctional xylanase/feruloyl esterase and its synergistic effects with cellulase on lignocellulose hydrolysis

Herein, the xylanase and feruloyl esterase domains of the xylanase/feruloyl esterase bifunctional enzyme (Xyn-Fae) from Prevotella ruminicola 23 were identified using N- and C-terminal truncation mutagenesis. In addition, a novel and more efficient xylanase/feruloyl esterase bifunctional enzyme XynII-Fae was constructed, and its synergistic action with a commercial cellulase for lignocellulose hydrolysis was studied. When 40% cellulase was replaced by XynII-Fae, the production of reducing sugars increased by 65% than that with the cellulase alone, and the conversions of xylan and glucan were increased by 125.1% and 54.3%, respectively. When 80% cellulase was substituted by XynII-Fae, up to 43.5 μg/mL ferulic acid and 418.7 μg/mL acetic acid were obtained. The XynII-Fae could also accelerate the hydrolysis of wheat straw and sugarcane bagasse with commercial cellulase. These results indicated that the synergistic action of XynII-Fae with cellulase could dramatically improve the hydrolysis efficiency of lignocellulose, showing the great potential for industrial applications.