Identification of the genes encoding biomass-degrading enzymes by microbial screening based on microdroplet deformability

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K05330
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 37020:Chemistry and chemical methodology of biomolecules-related
• Research Institution: The University of Tokyo
• Principal Investigator: Iizuka Ryo 東京大学, 大学院理学系研究科(理学部), 助教 (90541954)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 液滴 / マイクロ流体デバイス / 酵素 / スクリーニング

Outline of Final Research Achievements

Environmental microbes secrete enzymes capable of degrading macromolecules, such as agarose, into smaller molecules for cell growth. These enzymes can benefit the effective use of renewable natural resources such as biomass. However, most microbial cells remain unculturable and thus are inaccessible by culture-based methods. We then developed a culture-independent method for screening microbial cells that secrete polysaccharide hydrogel-degrading enzymes using deformability-based microfluidic microdroplet sorting. In this method, microbial cells are encapsulated as single cells in water-in-oil (W/O) microdroplets with hydrogel, whose shape becomes deformable as the hydrogel is progressively degraded into smaller molecules. Screening is achieved using a microfluidic device that passively sorts the deformed W/O microdroplets. Using this method, we successfully isolated single bacterial cells that hydrolyze agarose from seawater to identify agarase genes.

Free Research Field

生物物理学，タンパク質科学，バイオマイクロナノデバイス

Academic Significance and Societal Importance of the Research Achievements

世界で6番目の広さの海洋に囲まれる我が国では，安定的に大量供給が可能で食糧と競合しないリグノセルロース系バイオマス（セルロース，ヘミセルロース，リグニンなど）とともに，海藻バイオマス（アガロース，アルギン酸，フコイダンなど海藻多糖類）の有効利用が重要である．海藻多糖類はエタノールなどのエネルギー原料のみならず，付加価値の高い生理活性分子に変換可能である．しかし，海藻多糖類を効率よく分解できる酵素の報告は少ない．本研究で確立したスクリーニング法を駆使することで，優れた海藻多糖類分解酵素の取得が可能となる．