期刊
BIOMASS & BIOENERGY
卷 74, 期 -, 页码 122-134出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.biombioe.2015.01.016
关键词
Penicillium oxalicum; Cellulolytic enzymes; Culture supernatant; Agricultural wastes; Saccharification
资金
- Agricultural Ministry of China [2011-G27]
- Special Fund for Agro-scientific Research in the Public Interest [201203001]
- National key technology RD program [L020130249]
- Innovative Research Team Development Plan of the Ministry of Education of China [IRT1256]
- Qing Lan Project
A large amount of FPase (1.4 U/mL), CMCase (2.0 U/mL), cellobiohydrolase (0.6 U/mL), and beta-glucosidase (2.7 U/mL) activities were produced when Penicillium oxalicum 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 beta-glucosidase activity were 3.0 at 50 degrees C and 5.0 at 60 degrees C, respectively. The CMCase and beta-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 beta-glucosidase activity of P. oxalicum GZ-2 was 2.8 times greater than that of Trichoderma reesei RUT-C30. The culture supernatants of P. oxalicum 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 P. oxalicum GZ-2 than those from T. reesei 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. (C) 2015 Elsevier Ltd. All rights reserved.
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