Exploring and enrichment of hydrogen utilized N2O reducing bacteria using a gas-permeable membrane biofilm reactor

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K19988
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 64020:Environmental load reduction and remediation-related
• Research Institution: Hiroshima University (2021); Tokyo University of Agriculture and Technology (2020)
• Principal Investigator: Suenaga Toshikazu 広島大学, 先進理工系科学研究科(工), 助教 (80828377)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 亜酸化窒素 / 水素 / 集積培養 / アナモックス

Outline of Final Research Achievements

Nitrous oxide (N2O) is known as an ozone-depleting substance and a potent greenhouse gas. N2O-reducing bacteria, which are part of denitrifying bacteria, are a group of microorganisms that detoxify N2O into nitrogen. These bacteria generally use organic compounds as an electron donor, but we investigated whether they can also use hydrogen.
We determined the amount of N2O released from the anaerobic ammonia oxidation (anammox) process, which is an autotrophic environment, and found that the addition of hydrogen as an electron donor to the anammox biomass increased N2O reduction activity. In parallel, we carried out the enrichment of the bacteria by supplying hydrogen and N2O through a gas permeable membrane, but were unable to obtain the target bacteria, and we decided to continue the culture.

Free Research Field

化学工学、環境微生物学

Academic Significance and Societal Importance of the Research Achievements

これまで脱窒反応の電子供与体は原則として有機物の添加が必要であった。一方で、独立栄養的な環境に有機物を添加すると、従属栄養的な細菌群が増殖し、目的外の微生物群が優占化する危険性がある。今回、水素が独立栄養的環境下でN2O還元の電子供与体として利用可能であることが示唆されたことで、アナモックスプロセス等からのN2O抑制技術の開発への糸口になる可能性がある。本研究では結果的に水素資化性N2O還元細菌の獲得には至らなかったが、活性を見出す事はできたので、引き続き検討を勧めることで、有用微生物群の獲得とN2O放出抑制技術の開発に繋がると期待される。