成果報告書詳細
管理番号20110000000212
タイトル*平成21年度中間年報 新エネルギー技術研究開発 バイオマスエネルギー等高効率転換技術開発(先導技術開発) イオン液体を利用したバイオマスからのバイオ燃料生産技術の開発
公開日2011/4/1
報告書年度2009 - 2009
委託先名国立大学法人神戸大学 株式会社豊田中央研究所 国立大学法人九州大学 トヨタ自動車株式会社
プロジェクト番号P07015
部署名新エネルギー技術開発部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等
セルロース系バイオマスが新たな非可食性エネルギー原料として期待されている。しかし、セルロースは非常に結晶性が高い天然高分子で酵素分解速度は極めて遅いため、実用化の大きなボトルネックとなっている。本研究開発ではセルロースの結晶構造を緩和・脆化することができるイオン液体をバイオマスの前処理溶剤として用い、効率的な酵素分解およびエタノール発酵へと誘導する新プロセスの開発を目的とした。イオン液体を用いた前処理により、構造が脆化し、酵素によって分解されやすくなったセルロース系バイオマスに対し、セルロース分解能とエタノール発酵能を兼ね備えた酵母を用いることで、効率的かつ低エネルギーでのバイオ燃料生産を行うIonic liquid-based Consolidated Bio-Processing(i-CBP)の開発を行った。
英文要約Title: Development of ionic liquid-based consolidated bio-processing (i-CBP) (FY2009-FY2010) FY2009 Annual Report
Global climate changes have increased attention to the use of renewable biomass for energy production. Of the liquid energy sources, ethanol produced by the fermentation of glucose is a promising biomass-derived fuel. Since ethanol production from edible agricultural feedstocks is potentially problematic, researchers have focused on ethanol production from inedible biomass such as cellulose. For bioproduction of ethanol, cellulose should ultimately be hydrolyzed to glucose for fermentation by yeast. To accelerate the enzymatic hydrolysis of cellulose, we focus on ionic liquids, which can dissolve cellulose and decrease its crystallinity, as a pretreatment solvent. Pretreated cellulosic biomass by ionic liquids would be easily hydrolyzed to glucose. We have proposed an ionic liquid-based consolidated bio-processing (i-CBP), where pretreatment of biomass, enzymatic saccharification, and fermentation by yeast are integrated. Three types of lignocellulosic biomass including coniferous and broad-leaved tree were selected for the examination of ionic liquid pretreatment in enzymatic saccharification. The component of the biomass was analyzed by principle component analysis. The biomass were pretreated with several kinds of ionic liquids and then washed with water, followed by hydrolysis by cellulases. Some ionic liquids were found to give high saccharification efficiency compared with previous reports. Anionic species of ionic liquids would have an important role in the disruption of crystalline structure of cellulose. When an aqueous solution of cellulase was directly added to the ionic liquid-pretreated biomass, some ionic liquids greatly enhanced saccharification kinetics. Untreated lignocellulosic biomass did not generate glucose and cellobiose. Ionic liquid-treated biomass and untreated one were subjected to X-ray diffraction analysis to evaluate the degree of crystallization. Low crystalline nature of lignocellulosic biomass, which was validated by comparing the XRD patterns, could explain the difference in reactivity in enzymatic saccharification. However, the significant decrease in cellulase activity was observed in the high content of ionic liquids. In such cases, separation process of pretreated biomass from IL media will be necessary prior to enzymatic saccharification. We thus investigated the effect of ILs on such systems and found several ILs that can increase the yield of oligosaccharides from model lignocellulosic biomass. To study simultaneous saccharification cofermentation for i-CBP, we examined the direct ethanol production from ionic liquid-treated cellulose by cellulase-displaying yeast. Highly efficient ethanol production could be achieved by the functional yeast.
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