成果報告書詳細
管理番号20120000000212
タイトル*平成23年度中間年報 バイオマスエネルギー技術研究開発 戦略的次世代バイオマスエネルギー利用技術開発事業 (次世代技術開発) 非可食バイオマス由来混合糖からのバイオブタノール生産に関わる基盤技術開発
公開日2015/11/26
報告書年度2011 - 2011
委託先名バイオブタノール製造技術研究組合 国立大学法人東京工業大学
プロジェクト番号P10010
部署名新エネルギー部
和文要約
英文要約Title: Research and Development of Technology for Biomass Energy Conversion / Strategic Development for Next-generation Technology for Utilization of Biomass Energy / Development of Biobutanol Production Fundamental Technology from Non-edible Biomass Resources (FY2010-FY2013) FY2011 Annual Report

[1] Metabolic engineering of Corynebacterium glutamicum for butanol production Promotion of research and development of high biobutanol-producing strain ; 1-1) Search for enzyme with high substrate specificity and high enzymatic activity, 1-2) Conversion of cofactor requirement for adjustment of redox balance, 1-3) Elimination of by-product formation pathways in butanol production. Examination of reaction conditions of butanol production under growth-arrested bioprocess. The possibility of employing organic solvent as an extraction solvent to reduce end-product inhibition and to enhance butanol productivity in growth-arrested bioprocess was evaluated using oleyl alcohol as the butanol extractant. Applying oleyl alcohol as the extraction solvent, about 60% of the total butanol produced was extracted, and relatively high glucose consumption rates and butanol productivities were obtained. Development of butanol production from mixed sugars (C5 and C6 sugars) by growth-arrested bioprocess. C. glutamicum was genetically engineered to produce butanol from mixed sugars. Although the strain of mixed-sugar utilization produced butanol from glucose, xylose and arabinose under the growth-arrested bioprocess, its productivity was lower than that from glucose. This was attributed to imbalanced cofactor production and consumption in the butanol synthesis pathway. In order to solve this cofactor imbalance, coenzyme requirement was converted from NADPH to NADH via modification of acetohydroxy acid isomeroreductase encoded by ilvC. Furthermore, overexpression of the gapA gene encoding glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was also done. The intracellular NADH/NAD+ ratio significantly decreased, and mixed-sugars consumption and butanol production greatly improved. [2] Regulatory mechanism of sugar metabolism by RNase in Corynebacterium glutamicum;  Regulation of mRNA stability plays an important role in gene expression. The E. coli RNase G is involved in the degradation of mRNAs encoding glycolytic enzymes. In RNase G mutant cells, glycolysis is accelerated and pyruvic acid is consequently overproduced. These led us to investigate the characteristics of an RNase E/G family enzyme in an industrially important bacterium, Corynebacterium glutamicum. This microorganism has only one RNase E/G homolog, NCgl2281. We found that the NCgl2281 disruptant grew faster than wild type on acetate minimal medium. The NCgl2281 disruptant overproduced a glyoxylate cycle enzyme, isocitrate lyase, when grown on acetate minimal medium. Northern hybridization and primer extension analysis revealed that aceA mRNA encoding isocitrate lyase is a direct substrate of the NCgl2281 endoribonuclease. For these results, it is concluded that the NCgl2281 endoribonuclease is a negative regulator of the glyoxylate cycle in C. glutamicum. These findings can be applied for overproduction of enzymes involved in butanol production.
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