Smart removal of monosaccharide contaminants in xylo-oligosaccharide slurry using sandwich-integration bioprocess of whole-cell catalysis combined with electrodialysis separation

Abstract

Acetic acid hydrolysis is a green and novel approach that can effectively convert lignocellulosic biomass into high-valued xylo-oligosaccharide (XOS). However, the residual acidolysis slurry still contains acetic acid and various monosaccharides. In this study, a sandwich-integration bioprocess (SIBP) method was developed to efficiently remove the residual monosaccharide contaminants by the combination of whole-cell catalysis and electrodialysis separation. Firstly, the acetic acid in acidolysis slurry was separated by electrodialysis to eliminate the strong toxic inhibition on whole-cell catalysis. Secondly, the monosaccharides were oxidized to the corresponding ionogenic acids by whole-cell catalysis. Finally, these ionogenic aldonic acids were removed readily by the second electrodialysis step. Herein, whole-cell catalysis step was combined with two electrodialysis separation steps into SIBP, in which 131.4 g XOS and 79 g aldonic acids were obtained from 1 kg corncob and more than 93.1% acetic acid was recycled.