1998 Fiscal Year Final Research Report Summary
Studies on biodegration mechanism of cellulose by white-rotting fungi.
| Project/Area Number |
09660176
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
林産学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SAMEJIMA Masahiro Graduate School of Agricultural and Life Sciences, Associate Professor, 大学院・農学生命科学研究科, 助教授 (30162530)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Cellulase / Cellobiose dehydrogenase / Cellulose / Flavin / Cellobiohydrolase / Oxidoreductase / Phanerochaete chrysosporium / Biodegradation |
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| Research Abstract |
The white wood-rotting fungus Phanerochaete chrysosporium grown on cellulose produces the oxidoreductase cellobiose dehydrogenase (CDH). In this study, the role of CDH in cellulose degradation was investigated.
Adsorption of CDH is occurred only on the amorphous surface of cellulose, but not on the crystalline surface, suggesting that the function of CDH is not directly responsible for decomposition of the crystalline structure of cellulose.
In the static cultures of P.chrysosporium grown on cellulose, most of CDH activity is observed in the mycelium-cellulose complex, but not released in the culture solution. Moreover, localization of CDH on the cellulose surface is specialized to the crack formed by the action of cellulases. This observation is a good evicdence to suggest the cooperative function between cellulases and CDH in vivo.
The optimization of cultivation condition has been elaborated to obtain a large amount of CDH.The addition of calf bovine serum in the culture medium is resulted in the significant enhancement of CDH production in the extracellular solution. To investigated the reason of this phenomenon, the method using RT-PCR for measurement of the corresponding mRNA level have been established.
The interaction between cellobiohydrolase I (CBH I) and CDH in the decomposition of the microcrystalline bacterial cellulose was investigated The result demonstrated that the CDH redox system enhances CBH I activity by relieving the product inhibition.
The mechanism on pH dependence of electron transportation between flavin and heme cofactors in CDH was investigated. The result suggests that this phenomenon is caused by the pH depending conformational changes of the protein structure of the flavin containing domain.
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