2020 Fiscal Year Final Research Report

Research on the production and release of hydroxylamine derived from phytoplankton

Research Project

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Project/Area Number	19K22910
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Review Section	Medium-sized Section 63:Environmental analyses and evaluation and related fields
Research Institution	Shimane University
Principal Investigator	Seike Yasushi 島根大学, 学術研究院環境システム科学系, 特任教授 (30243421)
Co-Investigator(Kenkyū-buntansha)	管原庄吾島根大学, 学術研究院環境システム科学系, 講師 (30721302) 神門利之 (神門利之) 島根県保健環境科学研究所, 環境科学部, 部長 (70838408) 江川美千子島根大学, 学術研究院環境システム科学系, 助手 (20565882) 加藤季晋島根県保健環境科学研究所, 水環境科, 研究員 (20791734) 神谷宏島根県保健環境科学研究所, 環境科学部, 主任研究員 (50601928)
Project Period (FY)	2019-06-28 – 2021-03-31
Keywords	ヒドロキシルアミン / ラン藻類 / Dolichospermum crassum / 有光層 / 窒素代謝 / 単一無菌培養
Outline of Final Research Achievements	We have discovered an interesting phenomenon in which hydroxylamine (NH2OH) accumulates in high concentrations as Chl-a (a phytoplankton index) increases in the euphotic zone of a dam lake (reservoir). Furthermore, to investigate the presence or absence of NH2OH production by phytoplankton, a sterile culture strain of cyanobacteria (Dolichospermum crassum) isolated from the reservoir was used, and a culture experiment was conducted. As a result, a clear increase in NH2OH was confirmed, and the production and release of NH2OH by the cyanobacteria Dolicospermum crassum was clarified. This result suggests that NH2OH detected in the euphotic zone during the summer cyanobacteria outbreak was produced and released by the cyanobacteria. To our knowledge, there are no reports that NH2OH is produced and released by nitrogen metabolism in phytoplankton, which is probably the first observation to support the production of NH2OH derived from phytoplankton.
Free Research Field	環境化学，環境分析化学，生物地球化学
Academic Significance and Societal Importance of the Research Achievements	藍藻によるNH2OH産生の有無を調べるため、ダム湖から分離されたDolichospermum crassumの単一無菌培養株を用い、培養実験による検討を行ったところ、NH2OHの明らかな増加が確認された。我々が検索した限りでは、NH2OHの生成に対する植物プランクトンの関与を示す報告は国内外を問わず見当たらない（世界初の可能性あり）。本研究成果は、植物プランクトンには未知の窒素代謝プロセスが存在することを意味するものであり、本研究テーマは、学術体系の見直しを含む新たな発展性を有する可能性がある。