Development of a novel system for expression of termite cellulases and its application

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K14879
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Applied microbiology
• Research Institution: The University of Tokyo
• Principal Investigator: Arioka Manabu 東京大学, 大学院農学生命科学研究科(農学部), 准教授 (20242159)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: シロアリ / 共生微生物 / 糸状菌 / セロビオヒドロラーゼ / キシラナーゼ / マンナナーゼ / グルクロン酸エステラーゼ

Outline of Final Research Achievements

The expression of EuCBH, a cellobiohydrolase from a termite symbiotic protist, was attempted. When the enzyme was expressed in A. oryzae expressing AaBGL1, a beta-glucosidase (BG) from A. aculeatus, increased production was observed compared to the control strain not expressing AaBGL1. The expression of PaBG1b, a BG from wood-eating cockroach, fungal glucuronoyl esterases (GEs), and mannanases from termite symbiotic protists was also conducted. As results, PaBG1b and an A. fumigatus GE were shown to display higher catalytic efficiency than known enzymes. The importance of Trp residue located near the subsite -5 for the affinity to the substrate was also elucidated. Next, the expression and characterization of NtSymX11, an endoxylanase originated from a symbiotic bacterium in the gut of higher termite, were conducted. It was shown that the variants possessing the catalytic domain display 20-times higher catalytic performance compared to another endoxylanase with similar structure.

Free Research Field

応用微生物学

Academic Significance and Societal Importance of the Research Achievements

オオシロアリ共生原生生物由来セロビオヒドロラーゼEuCBHについては活性の確認には至らなかったが、本研究で新たに取得したbeta-グルコシダーゼPaBG1b、グルクロン酸エステラーゼAfGE、キシラナーゼNtSymX11については従来の酵素よりも高い比活性を有する酵素であることがわかり、今後期待されるバイオマス分解系構築において有力な候補であることを明らかにすることができた。