成果報告書詳細
管理番号20110000001085
タイトル*平成22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) 新規エタノール発酵糸状菌を活用した稲わら等の同時糖化発酵システムの開発
公開日2011/7/28
報告書年度2010 - 2010
委託先名国立大学法人富山大学、富山県立大学
プロジェクト番号P07015
部署名新エネルギー部
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 (1) エタノール発酵糸状菌の高度化(担当:富山大学) キシロース発酵糸状菌Mucor javanicus変異株を用いて通気攪拌型バイオリアクターによる好気培養を実施した。その結果、培養終了後菌糸と培養液の分離が容易にでき繰り返し回分操作が可能であることを実証した。さらに、この際Xylose発酵効率74%を達成できた。次に、本変異株の操作性を改善するために環境変化等による形態変化(二形成化)について検討した。
英文要約Title: New Energy Technology Development/Development to Technology for High-efficiency Conversion of Biomass and Other Energy. Development of SSCF System to Produce Ethanol from Rice Straw Using Novel Ethanol-fermenting Fungi (FY2008-FY2011) FY2010 Annual Reports.
In order to reduce the energy inputs required to efficiently produce ethanol from biomass such as rice straw generated from rice farming as agricultural residue, a simultaneous saccharification and cofermentation (SSCF) system that will use novel fungi is being constructed in this R&D project. In 2010, the following subtheme was investigated: (1) high-functionalization of ethanol-fermenting fungi, (2) research of pathway for metabolism and fermentation, (3) research of hydrolases secretion, (4) structural analysis of metabolism-related enzyme genes, and (5) development of SSCF. First, a M.javanicas mutant obtained by the ion-beam mutation was cultivated by using a conventional bioreactor under the aerobic condition. The strain could be separated easily from the broth after the batch culture and it was able to use for the following reaction continuously. Moreover, the mutant has a high ethanol fermentation efficiency of 74% on xylose. Further, an ion-beam mutation was executed to the conidiospore to improve the hydrolysis rate of rice straw in SSCF and then new mutants that were able to grow at 40 degrees were obtained. Next, to product effectively ethanol form fermenting-sugar existed in rice straw, it is extremely important to clarify exhaustively the metabolism flow for fermenting-sugars and for ethanol fermentation. Therefore, the metabolism analysis for mycelia grown by glucose and xylose was executed by using a CE-TOFMS. As these results, it was found that in xylose metabolism several intermediate compounds in pentose phosphate pathway and in purine synthesis pathway was irregular accumulated. Therefore, when the addition of vitamin supplementing the metabolism of pentose-phosphate pathway to the medium was performed to improve the stagnated metabolism flow, the improvement of ethanol production was able to be achieved with the repression of the growth. In theme 3, the acquisition of high cellulases-secreting mutants was carried out by irradiating ion-beam to a high xylose-fermenting mutant obtained by theme 1 to reduce the usage of hydrolases in SSCF. As the result, it succeeded in acquiring a high cellulase-secreting mutant for endo-beta-glucanase (EG) and xylanase (X). Moreover by discussing the culture condition of the strain the secretion amount of endo-beta-glucosidase (BG) was able to be improved up to about 88,000 times compared with that of a usual liquid shaking culture. In theme 4, to clarify exhaustively the metabolism related enzyme genes of M.javanicus (wild strain), the grafting analysis of genome was executed. As a result, the DNA array library of 34.7Mbp in the contig length was obtained. The genes coding EG, BG, and X was able to be confirmed from this library, respectively. Moreover, the cDNA cloning for xylose reductase, xylulokinase etc. was performed. Subsequently, the primary structures of purified enzymes were decided and it succeeded in appearance in the rearrangement E.coli, respectively. Definitely, the xylose metabolic pathway in the gene level of the strain was able to clarify. In theme 5, when the SSCF on 100 g/L rice straw prepared treatment and mechanical fine-grinding treatment was carried out with optimized cellulase agents and a developed xylose-fermenting mutant, 66 and 72% of fermentation efficiency was able to be achieved in 48 h, respectively.
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