1993 Fiscal Year Final Research Report Summary
The role of Cellobiose Dehydrogenases in Cellulose Biodegradation by Filamentous Fungi
| Project/Area Number |
04660176
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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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 The University of Tokyo, Faculty of Agriculture Assistant Proffessor, 農学部, 助手 (30162530)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Cellulose / Cellobiose / Biodegradation / Dehydrogenase / Oxidase / Oxidoreductase / Wood rotting fungi / Phanerochaete chysosporium |
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| Research Abstract |
The white rotting fungi, Phanerochaete chrysosporium, produces two types of cellobiose dehydrogenases, namely cellobiose oxidase (CBO) and cellobiose ; quinone oxidoreductase (CBQ), in the course of cellulose biodegradation. We have demonstrated that CBQ is derived from CBO by proteases co-exisisted in the culture medium of the later stage. Therefore, only CBO must be associated directly on cellulose biodegradation. I have revealed that the Fe (III) containing compound such as cytochrome c are more suitable electron acceptor than molecular oxygen, which was thought as a electron acceptor for CBO in the original article.
CBO is unable to solubilize cotton cellulose by itself, but also there is no obvious synergistic effects between cellulases and CBO on solubilization of cotton cellulose. From this result, CBO seems not to have any important role in the solubilization of cellulose. This idea is confirmed by the very low activity for the oxidation of the reducing ends in polymeric cellulose compared with those for cellodexrins. Furthermore, the CBO adsorption of cellulose occurs on a part of the amorphous surface.
From all these observations, the role of CBO in the cellulose biodegradation must be some important function of cellodextrin or cellobiose metabolism, for example, membrane transportation of metabolites or the linkage between metabolism of these compounds and energy production, rather than the decomposition of insoluble cellulose.
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