Abe, Kentaro

Horikawa, Yoshiki

Imai, Tomoya

Sugiyama, Junji

Kyoto University Research Information Repository

Title The structural changes in cellulose microfibril and theirsusceptibilities to cellulaseAuthor(s)Horikawa, Yoshiki; Imai, Tomoya; Abe, Kentaro; Sugiyama,JunjiCitationSustainable humanosphere : bulletin of Research Institute forSustainable Humanosphere Kyoto University (2014), 10: 1-1Issue Date2014-10-20URL http://hdl.handle.net/2433/196705RightType Departmental Bulletin PaperTextversionpublisherKyoto University RECENT RESEARCH ACTIVITIES 㻠㻜㻜㻜 㻟㻡㻜㻜 㻟㻜㻜㻜 㻞㻡㻜㻜㻟㻠㻤㻝㻵㻵㻵㻟㻟㻠㻡㻵㼣㼍㼢㼑㼚㼡㼙㼎㼑㼞 㻔㼏㼙㻙㻝㻕㻵The structural changes in cellulose microfibril and their susceptibilities to cellulase  (Laboratory of Biomass Morphogenesis and Information, RISH, Kyoto University)  Yoshiki Horikawa, Tomoya Imai, Kentaro Abe, and Junji Sugiyama   Lignocellulosic biomass is promising materials because of non-competition with food and it contains large amount of cellulose as a fermentable sugars. However, Cellulose is an insoluble crystalline polymer, which decreases the enzymatic hydrolysis from lignocellulose to monosaccharide. The efficient pretreatment, therefore, is required to enhance the susceptibility of cellulose by removing the matrix component as well as modification of cellulose structural property, which leading the reduction of enzyme dosage.   Therefore, we prepared well-dispersed microfibriller cellulose from Eucalyptus globulus by mechanical grinding and used as starting substrate [1]. The digestibility of this cellulose I achieves almost complete digestion when sufficient commercial cellulase loading as much as 20mg/g-substrate is applied. However, when the enzyme dosage is decreased to 2mg/g-substrate, the yield of digestion reaches the limit. Therefore, we have performed three pretreatment such as mercerization, dissolution into phosphoric acid and ethylenediamine (EDA) treatment. Transformation into cellulose II hydrate by mercerization and dissolution into phosphoric acid were not sufficient because substrate changed to highly crystalline structure during saccharification. On the other hand, in the case of crystalline conversion of cellulose I to IIII by EDA, almost perfect hydrolysis was achieved even in enzyme loading as small as 0.5 mg/g-substrate, furthermore, hydrolyzed residue was changed to typical cellulose I (Figure), which clearly demonstrated cellulose I is more recalcitrant substrate compared to cellulose IIII. The structural analysis of substrate after digestion gives an insight into interaction of cellulose crystalline property and cellulase for better enzymatic digestion.    Acknowledgement The authors express their appreciation to Ms. K. Kanai and Ms. M. Imai for their technical support on the research. This study was supported by the New Energy and Industrial Technology Development Organization (NEDO).  Reference [1] Horikawa, Y., Konakahara, N., Imai, T., Abe, K., Kobayashi, Y., Sugiyama, J. (2013) The structural changes in crystalline cellulose and effects on enzymatic digestibility. Polym. Degrad. Stabil., 98 (11), 2351-2356.   Figure FTIR spectra of cellulose IIII before (bold line) and after enzymatic hydrolysis (hair line). The bands at 3345 and 3481 cm-1 are specific to cellulose I and IIII, respectively. 1Sustainable Humanosphere, vol. 10, p.1, 2014

The structural changes in cellulose microfibril and their susceptibilities to cellulase

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The structural changes in cellulose microfibril and their susceptibilities to cellulase

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