Abstract: Enzymatic hydrolysis of corncob for ethanol fermentation from cellulosic hydrolysate was investigated. Corncob pretreated with dilute sulfuric acid was hydrolyzed by the cellulase from Trichoderma reesei ZU-02 at 50℃, pH value 4.8, and the hydrolysis yield was only 67.5% due to poor cellobiase activity in T. reesei ZU-02 cellulase. Addition of cellobiase from Aspergillus niger ZU-07 greatly reduced the inhibitory effect caused by cellobiose, and the hydrolysis yield was improved to 83.9% with cellobiase dosage of 6.5 CBIU/g substrate. A hydrolysis process using batch-wise feed was carried out to get a final substrate concentration of 200 g/L and the hydrolysis yield reached 80.1% after 60 h reaction. Furthermore, ethanol fermentation of cellulosic hydrolysate containing 95.3 g/L glucose was performed at 38℃ using a thermotolerant strain Saccharomyces cerevisiae HTR-11,45.7 g/L ethanol was obtained within 18 h and ethanol yield reached 94% of the theoretical yield.

Key words: corncob, hydrolysis, cellulase, cellobiase, ethanol fermentation