Isolation And Solid-state Fermentation Of The High-producing Cellulase Fungus And Purification Of Its Cellulases

A novel Aspergillus terreus strain Mll was isolated from the compost containing cellulose and identified.Factors effectiing on cellulase production during solid State fermentation(SSF) and liquid fermentaion were studied.The results show The isolate both grow best at 45℃and pH2.0 under two fermentaion.styles.It was found that the activity of the endoglucanase was up to 3.68U/ml under liquid fermentaion.Under SSF,581 U endoglucariase activity,243 U filter paper activity and 128 U B-glucosidase activiy per g of carbon source were obtained.Endoglucanase produced under liquid fermentation was active optimally at pH2 and 60℃.It maintained 68%of the original activity after incubation at 50℃for 30min.the enzyme was stable from pH2 to 4.Endoglucanase and B-Glucosidase produced under SSF exhibited its maximum activity at pH 2 and pH 3,respectively.The optimal temperature of both cellulases was 70℃.The cellulases exhibited remarkable stability in the range of pH 2-5.The activities of endoglucanase and B-Glucosidase were maintained 65%and 53%of their original activities after incubation at 70℃for 6h.The produced cellulase could effectively hydrolyze Avicel,and the yield of enzymatic hydrolysis reached 63%on 5%Avicel(w/v) when the cellulase dosage was 20 U FPase/g substrate.Besides,an endoglucanase from a thermoacidophilic fungus,Aspergillus terreus Mll, was purified 18.30-fold with 13.76%yield and a specific activity of 67.34U mg^-1 protein. The optimal pH was 2 and the cellulase was stable from pH 2 to 5.The cellulase had.a temperature optimum of 60℃measured over 30 min and retained more than 60%of its activity after heating at 70℃for 1 h.The molecular mass of the cellulase was about 25 kDa. Its activity was inhibited by 77%by Hg²⁺(2 mM) and by 59%by Cu²⁺(2 mM).