| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程學系 === 101 === The strain used in this study was Aspergillus niger which could product lots of cellulase by solid state fermentation. Traditional saccharification method used commercial purified cellulase. In the recent year, there were some operating which producing celluase from microorganisms, but it still need to extract crudely or separate the microorganism. A novel method in saccharification step is proposed to easily operate in this study. By controlling environmental parameters like temperature or oxygen to inhibit the growth of Aspergillus niger, the culture resulted in the accumulation of reducing sugar. The operation not only remove the complex steps but also achieve the target of cost down. Cellulase activity is the main controlling factor in the saccharification step, thus we proposed to extend the method of cellulase activity. Finally, ethanol was obtained by Saccharomyces cerevisiae after saccharification fermentation broth.
The experimental results show that solid-state fermentation can produce higher unit cellulase activity, and the highest cellulase activity obtained as 23.85 U/gdm by soybean and rice straw. Saccharification step could be utilized to enhance the enzyme activity and to inhibit the growth of Aspergillus niger by increasing temperature. Anaerobic operating can inhibit Aspergillus niger as a result that the reducing sugar was produced at the second step. In the saccharification step, adding 20 g/L of alkali-treated rice straw can obtain the highest 11.58 g / L of reducing sugar, the conversion efficiency was 58.42%. Adding PMSF as a protease inhibitor or adding more cellulase was can extend the cellulase activity. Applied to the fermentation of ethanol, the maximum ethanol concentration can be obtained as 2.00 g / L and the conversion efficiency as 86.71%.
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