Improving catalytic efficiency of endoxylanase for degrading corncob xylan to produce xylooligosaccharides by fusing a β-xylosidase

A robust endoxylanase with high activity has great potential in biomass utilization. Here, the catalytic efficiency of the endoxylanase XynF derived from Herbinix hemicellulosilytica was improved by fusing a beta-xylosidase xln-DT derived from Dictyoglomus thermophilum with linkers (L0 and L3) and the direction from xln-DT to XynF. The biochemical properties and application potential of chimeras towards corncob xylan were explored. The result showed that the chimeras Xln-L0-XynF and Xln-L3-XynF exhibited higher catalytic efficiency (31-fold and 20-fold enhancement, respectively), and maintained high stability in some harsh environments compared with parental enzymes. This might be attributed to the appropriate linkers and the direction which decrease the adverse interactions between the two modules. These two chimeras could hydrolyze corncob xylan to produce approximately 30% xylooligosaccharides with polymerization of 2-6. This work represents the promising xylanases for participating in XOS production from an abundant corncobs and promote us to modify glycoside hydrolase by fusion technology.