Application of Bacillus pumilus β-xylosidase reaction and simulated moving bed purification to efficient production of high-purity xylobiose from xylose

Xylobiose (X2) is recognized to possess great prebiotic function and to be highly favorable for application in food and prebiotic industries. In this study, we demonstrated that the cloned β-xylosidase of Bacillus pumilus IPO could be utilized to produce X2 via the reaction of xylose(X1)→xylobiose(X2). The use of such enzyme in the X1→X2 reaction was found to give much higher X2 reaction yield and reaction efficiency, compared to those reported in the literature. Furthermore, we developed an efficient simulated moving bed (SMB) chromatographic process that could recover X2 from the reaction output with nearly 100% purity and 92% recovery on a continuous-separation mode. The developed SMB process could also recover the unreacted X1 almost completely, which leaves room for a further increase in the overall X2 reaction yield by reusing the recovered X1 from the SMB as the reactant of the upstream processing (i.e., B. pumilus IPO β-xylosidase X1→X2 reaction). The results of this study will enable a highly economical and environmentally-friendly production of high-purity X2 from X1.