초록
<P><B>Abstract</B></P> <P>A large amount of FPase (1.4U/mL), CMCase (2.0U/mL), cellobiohydrolase (0.6U/mL), and β-glucosidase (2.7U/mL) activities were produced when <I>Penicillium oxalicum</I> GZ-2 was grown on rice straw in a 5 L bioreactor. The zymography demonstrated that the expression abundance of cellulose-degrading proteins (35–70 kDa) responded to high cellulolytic enzymes activity. Cellobiohydrolase, exo-beta-1,3-glucanase, endo-beta-1,4-glucanase, swollenin, and other glycoside hydrolases were identified in visible hydrolyzed bands in zymogram gel using MALDI-TOF-MS/MS. The relative proportions of cellulose-degrading proteins were 50.0%, 45.7%, and 44.1% in the crude enzymes induced by wheat straw, rice straw, and corn stover, respectively. It suggested that the majority of extracellular proteins were cellulose-degrading enzymes induced by agricultural wastes. The optimized pH and temperature for CMCase and β-glucosidase activity were 3.0 at 50 °C and 5.0 at 60 °C, respectively. The CMCase and β-glucosidase showed remarkable stability at pH 4.0–9.0 and 3.0–7.0 with 80% of the maximum activity, respectively. Although the FPase activity was similar, the β-glucosidase activity of <I>P. oxalicum</I> GZ-2 was 2.8 times greater than that of <I>Trichoderma reesei</I> RUT-C30. The culture supernatants of <I>P. oxalicum</I> GZ-2 showed more efficiently capability to enzymatic hydrolysis of Avicel and corncob compared to commercial cellulase. For the saccharification of alkali-pretreated corncob, a higher reducing sugar and glucose yield was obtained using the culture supernatants from <I>P. oxalicum</I> GZ-2 than those from <I>T. reesei</I> RUT-C30. However, the highest sugar yields obtained from the mixture of enzymes indicated that a better design cocktail was also important for hydrolyzing biomass.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>