| Popis: |
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) NaNO 3 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. |
Full Text from ScienceDirect