An environment friendly and efficient process for xylitol bioconversion from enzymatic corncob hydrolysate by adapted Candida tropicalis

•A green process was developed for hydrolysate preparation and xylitol production.•Different conditions were investigated to improve xylanolytic enzymes production.•Different parameters were optimized to prepare corncob hemicellulose hydrolysate.•High xylitol yield was obtained from hydrolysate by adapted Candida tropicalis.

This study reported an environment friendly process for xylitol bioconversion from corncob hemicellulose hydrolysate prepared through xylanolytic enzymes by adapted Candida tropicalis. In order to improve the production of xylanolytic enzymes from Aspergillus terreus, the fermentation medium and growth conditions were optimized. Maximum xylanase (722 U/g) and β-xylosidase (196 U/g) production were exhibited on wheat bran and corncob (mass ratio of 7:3) medium supplemented with 2% (v/v) NaNO3 and 0.05% (v/v) Tween 80 at pH 6.8, 1:1 (v/w) moisture level, 20% inoculum level and 30 °C for 120 h of cultivation. For preparation of corncob hemicellulose hydrolysate, the optimum enzymatic hydrolysis conditions contained enzyme dosage (30.6 U/g), water addition (19.2 mL/g), temperature (48.01 °C), pH (5.75). Under these conditions, the sugars of 18.03 g/L xylose and 4.87 g/L glucose were obtained in 8 h. The corncob hemicellulose hydrolysate was used for xylitol fermentation and the maximum xylitol yield of 75.14% was obtained by adapted C. tropicalis after the optimization of fermentation.