Generating Fermentable Sugars from Rice Straw Using Functionally Active Cellulolytic Enzymes from Aspergillus niger HO

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• 作者：Rekha Rawat ; Neha Srivastava ; Bhupinder Singh Chadha ; Harinder Singh Oberoi
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：August 21, 2014
• 年：2014
• 卷：28
• 期：8
• 页码：5067-5075
• 全文大小：321K
• ISSN：1520-5029

文摘

Among the three Aspergillus spp. (A. niger, A. oryzae, and A. fumigatus) screened for cellulolytic enzyme production potential, A. niger produced cellulolytic enzyme in relatively higher concentrations than the other two isolates. Enzyme produced by all three isolates was optimally active at pH 5.0. Cellulases from A. niger and A. fumigatus were optimally active at 55 掳C, while the enzyme from A. oryzae showed optimum activity at 50 掳C. Cellulase from A. niger and A. fumigatus retained more than 80 and 70% activity, respectively, while cellulase from A. oryzae could retain only 20% activity at 55 掳C after 12 h. Cellulase from A. niger exhibited better stability at higher temperatures than the enzyme from the other two Aspergillus spp., showing half-life (t_1/2) of about 5 and 3 h at 70 and 80 掳C, respectively. Zymogram revealed multiple forms of endoglucanase, cellobiohydrolase, and 尾-glucosidase with molecular mass ranging between 28 and 154 kDa for cellulase from all three isolates. Hydrolysis of rice straw at 12.5% (w/v) with crude cellulase from A. niger HO resulted in fermentable sugar concentration and productivity of 66.2 g L^鈥? and 2.75 g L^鈥? h^鈥?, respectively, showing potential for the reported enzyme in biofuel industry.