Production and characterization of cellulolytic enzymes from the thermoacidophilic fungal Aspergillus terreus M11 under solid-state cultivation of corn stover

The production of extracellular cellulases by a newly isolated thermoacidophilic fungus, Aspergillus terreus M11, on the lignocellulosic materials was studied in solid-state fermentation (SSF). The results showed that the high-level cellulase activity was produced at 45 °C pH 3 and moisture 80% with corn stover and 0.8% yeast extract as carbon and nitrogen sources. 581 U endoglucanase activity, 243 U filter paper activity and 128 U β-glucosidase activity per gram of carbon source were obtained in the optimal condition. Endoglucanase and β-glucosidase exhibited their maximum activity at pH 2 and pH 3, respectively, and both of them showed remarkable stability in the range of pH 2-5. The activities of endoglucanase and β-glucosidase were up to the maximum at 70 °C and maintained about 65% and 53% of their original activities after incubation at 70 °C for 6 h. The enzyme preparations from this strain were used to hydrolyze Avicel. Higher hydrolysis yields of Avicel were up to 63% on 5% Avicel (w/v) for 72 h with 20 U FPase/g substrate.