High temperature xylitol production through simultaneous co-utilization of glucose and xylose by engineered Kluyveromyces marxianus

Abstract

Abstract Xylitol production from lignocellulose-hydrolyzed glucose and xylose is a sustainable and environment-friendly process. In this study, Kluyveromyces marxianus YZB194, constructed by overexpressing ScGAL2N376F from Saccharomyces cerevisiae and NcXYL1 from Neurospora crassa, and deleting GPD1, KU70, PGI1, and XYL2, was used for xylitol production by co-utilizing glucose and xylose. By deleting PGI1, the glucose repression effect on xylose in K. marxianus was released, besides, glucose metabolism in YZB194 was refactored through the pentose phosphate pathway, a pathway yielding the largest supply of NADPH in yeast. The metabolic pathway of xylitol was blocked by deleting of XYL2. By simultaneously co-utilizing 70 g/L glucose and 140 g/L xylose, 139.96 g/L xylitol with a productivity of 0.83 g/L/h was obtained by YZB194 at 37 °C under aerobic conditions. Through fed-batch fermentation in a fermenter at 42 °C, 203.57 g/L xylitol with a productivity of 2.99 g/L/h and yield on xylose of 0.99 g/g were obtained using K. marxianus YZB194. A platform for xylitol production by co-utilizing glucose and xylose via rewriting the glucose metabolism pathway was implemented.