Biofuel is currently produced from starch/sugar biomass, such as corn and sugarcane. However, use of such food resources for fuel production brings about social and ethical problems and the establishment of a new technology that enables use of non-edible cellulose biomass is urgently needed. "Soft-biomass", such as agricultural waste (straw and corn stover) and switch grass, contain relatively low amounts of lignin and are regarded as good candidates to use in biorefinery. In the future, use of "hard-biomass" (wood biomass) is expected.
 The novel cellulose biomass saccharification technologies we are aiming to develop are based on:
 1. A cellulolytic enzyme complex, "cellulosome"
 2. Cellulolytic enzymes from wood rotting fungi
 3. A continuous saccharification system that re-uses saccharification enzymes

1. Utilization of a cellulolytic enzyme complex, "cellulosome"
 Recently, the anaerobe, Clostridium sp. and a few other anaerobic bacteria were shown to harbor protein complexes called cellulosomes, which possess >10 fold activity compared to well-known cellulases. Introduction of the cellulosome functions into industrially useful bacteria by using genetic engineering techniques would make possible development of an innovative saccharification technology from soft biomass resources.

2. Utilization of cellulolytic enzymes from wood rotting fungi
 Wood rotting fungi (Basidiomycota) are able to degrade the whole wood components (cellulose, hemicellulose and lignin etc.). By utilizing such cellulolytic enzymes we aim to construct a highly efficient saccharification system optimized to degrade wood biomass (hard biomass).

3. Utilization of a continuous saccharification system that re-uses saccharification enzymes
 A large part of the cost in the cellulose-biomass saccharification process comes from saccharification enzymes. By using this technology we have succeeded in reducing the amount of enzymes needed to saccharify recycled paper. We now aim at a further cost reduction by combining this technology with the novel enzymatic system mentioned above.

< References >
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Effect of carbon source on the cellulosomal subpopulations of Clostridium cellulovorans.
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S.O. Han, H. Yukawa, M. Inui and R.H. Doi.

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H-Y. Cho, H. Yukawa, M. Inui, R.H. Doi and S-L. Wong.

Regulation of expression of cellulosomes and noncellulosomal (hemi)cellulolytic enzymes in Clostridium cellulovorans during growth on different carbon sources.
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S.O. Han, H-Y. Cho, H. Yukawa, M. Inui and R.H. Doi.

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