Production of xylitol by Saccharomycescerevisiae using waste xylose mother liquor and corncob residues.

Abstract

SummaryExorbitant outputs of waste xylose mother liquor (WXML) and corncob residue from commercial‐scale production of xylitol create environmental problems. To reduce the wastes, a Saccharomyces cerevisiae strain tolerant to WXML was conferred with abilities to express the genes of xylose reductase, a xylose‐specific transporter and enzymes of the pentose phosphate pathway. This strain showed a high capacity to produce xylitol from xylose in WXML with glucose as a co‐substrate. Additionally, a simultaneous saccharification and fermentation (SSF) process was designed to use corncob residues and cellulase instead of directly adding glucose as a co‐substrate. Xylitol titer and the productivity were, respectively, 91.0 g l‐1 and 1.26 ± 0.01 g l‐1 h‐1 using 20% WXML, 55 g DCW l‐1 delignified corncob residues and 11.8 FPU gcellulose ‐1 cellulase at 35° during fermentation. This work demonstrates the promising strategy of SSF to exploit waste products to xylitol fermentation process.