Development of an ammonia-inhibition control system in microalgal cultivation

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14903
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Japan Agency for Marine-Earth Science and Technology (2022); Soka University (2021)
• Principal Investigator: Kishi Masatoshi 国立研究開発法人海洋研究開発機構, 地球環境部門(地球表層システム研究センター), 特別研究員(PD) (00824020)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: 微細藻類 / アンモニア / 阻害 / クロロフィル蛍光 / モニタリング / 循環型社会

Outline of Final Research Achievements

Microalgae have the potential to produce valuable products using nutrients and CO2 derived from organic waste, contributing to the formation of a circular society. However, a significant portion of the nutrients is in the form of toxic ammonia (NH3), making direct utilization challenging. If we can control the supply to ensure that NH3 concentration remains below inhibitory levels, direct utilization of waste becomes possible. In this study, we aimed to establish a fluorescent-based NH3 inhibition detection method. The results revealed that fluorescence analysis using multiple excitation wavelengths and pulse-modulated fluorescence analysis can detect ammonia inhibition within a few minutes of exposure. Furthermore, by combining multivariate analysis, it was possible to mitigate variations caused by environmental factors.

Free Research Field

環境工学

Academic Significance and Societal Importance of the Research Achievements

これまで無希釈消化液などの高濃度アンモニア含有水を直接供給して藻類培養に成功した例は耐性の極端に強い種などに限られるが、本研究で開発している技術が実現すれば、ほとんどの藻類種で直接供給を可能にする。さらに、クロロフィル蛍光と多変量解析との組み合わせにより、アンモニア阻害だけでない広範な藻類の生理状態判別および大量培養の生産性向上に応用できると期待される。