Production of xylitol in cell recycle fermentations of Candida tropicalis

Xylitol was produced a in two-substrate, batch fermentation with cell recycling of Candida tropicalis ATCC 13803. A series of cell-recycle experiments showed that the feeding of xylose, glucose and yeast extract in the xylitol production phase was most effective in enhancing xylitol productivity. The optimized cell recycle fermentation resulted in 0.82 g xylitol/g xylose yield, 4.94 g xylitol l(-1) h(-1) productivity, and final xylitol concentration of 189 g l(-1). These results were 1.3 times higher in volumetric xylitol productivity and 2.2 times higher in final product concentration compared with the corresponding values of the optimized two-substrate batch culture.