Steam explosion pretreatment of corn straw on xylose recovery and xylitol production using hydrolysate without detoxification

Abstract The composition of the liquid fraction (hydrolysate) obtained from the steam explosion pretreatment of corn straw was investigated. Non-detoxified hydrolysate was used in a medium for xylitol production using Candida tropicalis . The inhibitors in the hydrolysate strongly affected the cell growth of C. tropicalis , causing a reduction of as much as 35% in the maximum specific growth rate compared with that observed for the medium without the addition of hydrolysate. The inhibition of hydrolysate can be overcome by increasing the inoculum size to 1.6 g l −1 . Via xylitol fermentation, which involves a high inoculum size strategy, a maximal xylitol concentration of 35.6 g l −1 was obtained after 38 h of fermentation; furthermore, the productivity was 0.94 g l −1  h −1 , and the xylose yield was 0.71 g g −1 .