Monday, April 19, 2010
3-29

Producing mechanism and lignocellulosic biomass hydrolyzing ability of the enzymes produced by cellulase hyper-producing mutants derived from the fungus Trichoderma reesei QM9414

Tatsuya Fujii, Katsuji Murakami, and Shigeki Sawayama. Biomass Technology Research Center, National Institute of Advanced Industrial Science and Technology, 2-2-2 Hiro-suehiro, Kure, Japan

The fungus Trichoderma reesei QM9414 secretes a large amount of cellulase, which was treated with various mutagens, and cellulase hyper-producing mutants were obtained. We investigated cellulase production mechanism of two mutants, T. reesei X31 and T. reesei PC-1-4, by analyzing the cellulase activity and transcription of cellulase genes. When these strains were cultured in a medium containing Avicel as a carbon source, filter-paper degrading enzyme activities of these mutants were increased by 1.5 to 3.5-fold higher than that of QM9414. In addition, realtime-PCR analyses revealed that the transcription of cellobiohydrolase I gene and endoglucanase I gene of these mutants were also increased as compared with those of QM9414. Similar results were obtained when the strains were cultured with ball-milled eucalyptus as a carbon source. These results suggested that mutations of these mutants affected cellulase production at transcriptional level. It is important for bioethanol production to investigate biomass saccharification ability of enzyme mixture, and we analyzed hydrolyzing performance of enzyme mixture derived from the mutants. Used enzyme mixture were that derived from T. reesei CDU-11 (ETR), which was mutant derived from QM9414, and that derived from the fungus Acremonium cellulolyticus CF-2612 (EAC), which was cellulase hyper-producing mutant. Hydrolyzed lignocellulosic materials were eucalyptus, Douglas fir and rice straw. The EAC glucose yield for each materials after hydrolysis for 3 h and 72 h were higher and equally compared with ETC, respectively, indicating that EAC hydrolyzed the materials faster than ETC. This suggests that EAC is superior to ETC on biomass hydrolyzing performance.

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