Monday, May 4, 2009
5-44
Comparison of the hydrolytic activity of different cellulase to develop simultaneous saccharification and fermentation process of pretreated rice straw
Deng-Chieh Hsu, Gia-Luen Guo, Sheng-Hsin Chou, and Wen-Song Hwang. Institute of Nuclear Energy Research, no. 1000, Wenhus Road, Jiaan Village, Longtan,Taoyuan, Taoyuan, Taiwan
Rice straw is the most abundantly agricultural waste in Asia and the potential amounts are estimated to be 670 million tons one year. To date, most of study in the development of cellulase was concentrated on the saccharification of pretreated corn stover; less research was paid attention to understand the influence of cellulase composition on enzymatic hydrolysis of pretreated rice straw. This study was aimed to develop a simultaneous saccharification and fermentation process for pretreated rice straw by means of specifying the saccharification ability of different industrial cellulase. The pretreated rice straw was prepared by dilute sulfuric acid pretreatment with a pressurized reactor. The results of saccharification were indicated β-glucosidase activity determined with salicin as the substrate was proposed to be above 50U/ml under 15FPU/g cellulose of enzymatic loading. This is useful to avoid the accumulation of cellobiose during hydrolytic reaction. The level in activity of exoglucanase was more significant than that of endoglucanase for enzymatic hydrolysis of pretreated rice straw. The enhancement in the sugar yield was obvious when the exoglucanase activity of cellulase was more. The maximal glucose yield from enzymatic hydrolysis at 50°C was achieved to be 80-85%. Moreover, the highest ethanol yield from SSF process at 38°C was found to be about 75%, where conversion from saccharification and fermentation was nearly 80% and 94%, respectively. Consequently, the ethanol conversion from SSF process of pretreated rice straw was suggested to be under industrial interest and then shown potential for further scale-up experiments.