Research on a novel fungal enzyme that degrades biodegradable polymer PHB

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K21324
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 40:Forestry and forest products science, applied aquatic science, and related fields
• Research Institution: Hokkaido University
• Principal Investigator: Inoue Akira 北海道大学, 水産科学研究院, 教授 (70396307)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: 生分解性ポリマー / ポリヒドロキシアルカン酸 / ポリヒドロキシブチレート / 分解酵素 / 異種細胞発現 / 組換え酵素

Outline of Final Research Achievements

As an alternative material to petroleum-based plastics, there are polyhydroxyalkanoates (PHA) such as polyhydroxybutyrate (PHB) and copolymers of 3-hydroxybutyrate (3HB) and 3-hydroxyhexanoate (3HH), which are biodegradable polymers. In this study, a novel fungus strain SEA-51 was isolated from beach sand, which can grow solely using PHB as a carbon source, and it was revealed that its PHB-degrading enzyme consists of at least two types of oligomers. Furthermore, one of these proteins was found to be responsible for the degradation of both PHB and PHBH. In addition, an expression system for recombinant degradation enzymes with activity using insect cells was constructed, and it was demonstrated that the obtained enzyme has activity equivalent to that of the natural enzyme.

Free Research Field

海洋生物工学

Academic Significance and Societal Importance of the Research Achievements

近年、PHB(H)を素材とする生分解性プラスチックの生産と需要が年々増大している。これらが自然界に流出すると、生物による分解が期待されるものの、地球上の生物がもつ分解能力は無限ではない。分解能力を超えた場合には、石油系プラスチックと同様の問題や生態系にネガティブな影響を与えると考えられる。そのような問題が生じる前に、優れた分解能をもつPHB(H)分解酵素を探索し、組換え酵素として選択的かつ大量に生産する技術開発が重要となる。本研究では、活性型PHB(H)分解酵素の分泌発現系の構築に成功した。このように、将来懸念される課題の解決に貢献する基盤技術の構築に成功した意義は大きい。