成果報告書詳細
管理番号20100000001235
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) 大腸菌によるイソプロパノール生産の研究開発
公開日2010/9/9
報告書年度2009 - 2009
委託先名九州大学 神戸大学
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 本研究では、セルロースおよびキシランからイソプロパノールを直接発酵により生産する大腸菌の分子育種およびバイオプロセスの開発を実施する。そのため、大腸菌を用いた糖からのイソプロパノール生産向上を目指した「代謝工学によるイソプロパノール生産向上の研究開発」を九州大学が、セルロースおよびキシランからの直接発酵を目指した「細胞表層工学によるセルラーゼの表層提示大腸菌の研究開発」を神戸大学が担当する。
(1)代謝工学によるイソプロパノール生産向上の研究開発 (九州大学)
(2)細胞表層工学によるセルラーゼの表層提示大腸菌の研究開発(神戸大学)
英文要約Title: Development of Technology for High-efficiency Conversion of Biomass and Other Energy/Development of Preparatory Basic Bioenergy Technologies/Research and Development to Improve Production through the Use of Engineered E. coli (FY 2008-2009) FY 2009 annual report.
1) To improve isopropanol production from glucose using E. coli, optimization of fermentation condition, isopropanol removal by gas stripping, and optimization of metabolic pathway were carried out.Using a pH-controlled fed-batch culture with the intermittent addition of glucose, strain TA76 produced 667 mM (40.1 g/l) of isopropanol after 60 h, representing 73.2% (mol isopropanol/mol glucose) of the theoretical maximum yield. As the accumulation of isopropanol drastically reduced production yields, a gas stripping recovery method was incorporated into the fed-batch culture system. Using this approach,strain TA76 produced 2,378 mM (143 g/l) of isopropanol after 240 h with a yield of 67.4% (mol/mol). To our knowledge, this titer represents the highest level of isopropanol production by E. coli to date and suggests that strain TA76 has a great potential for commercial fermentative isopropanol production.In order to improve isopropanol production, we deleted the host pathways that compete with the isopropanol pathway for acetyl-CoA. The deletion of ldhA, adhE, pta, and the combination of these genes were applied to isopropanol production. A yield of isopropanol from glucose by the deletion of ldhA was better than that by the wild type and a titer by the deletion of adhE was better than that by the wild type.2) For displaying of cellulase on surface of E. coli, a membrane localized domain PgsA of poly-gamma glutamine synthase from Bacillus subtilis was used as an anchor. In this year, the b-glucosidase, one kinds of cellulase, was chosen for displaying, and selected following species; Clostridium cellulovorans bglA, Lactobacillus plantarum bglA,Lactococcus lactis IL1403 yidC, Lactococcus lactis IL1403 bglS, Lactococcus lactis IL1403 bglH, Lactococcus lactis IL1403 ypcA, Corynebacterium glutamicum bglY, Corynebacterium glutamicum bglS, and S. degradans b-glucosidase. As a result, Clostridium cellulovorans bglA and S. degradans b-glucosidase exhibited its BGL activity by displaying on the surface of E. coli, and these displayed transformant also could grow in the cellobiose sole culture medium.
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