Hydrophobic effects enhance xylooligosaccharides production from mulberry branch using xylanase-methacrylate conjugate-catalyzed hydrolysis

Abstract

Xylooligosaccharides have received widespread attention as a high-quality non-renewable resource due to the global shortage of resources. However, it remains challenging to address both the stability and catalytic activity of biocatalysts throughout the preparation process. Herein, three XYL-polymer conjugates were synthesized by grafting monomeric compounds containing C2-C4 alkyl chains onto the surface of xylanase using an atom transfer radical polymerization (ATRP) “grafting from” strategy. Besides, the results show that the stability and catalytic efficiency of the conjugates were improved, and the degree of lifting was found to be related to the hydrophobicity of the monomer. Among them, XYL-pBMA could remain at 67.61% relative activity after treatment at 90 °C for 1 h which was 12.3 times of free xylanase. And the catalytic efficiency of XYL-pBMA was 1609.40 mL/s/mg which was 1.3 times that of free xylanase. Furthermore, XYL-pBMA still retains more than 60% of residual activity after 7 reuses. In addition, the mulberry branch was hydrolyzed via the synergistic action of XYL-polymer conjugates and cellulase. The reducing sugar concentration reached 8.72 mg/mL, and more than 99% of the oligosaccharide riched in xylose, xylobiose, and xylotriose. Accordingly, xylanase-methacrylate conjugates to produce oligosaccharides from mulberry branch are an efficient and sustainable method.