The development of innovative nitrification and denitrification process using anoxygenic phototrophic bacteria

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H06243
• Research Category: Grant-in-Aid for Challenging Research (Pioneering)
• Allocation Type: Single-year Grants
• Research Field: Agricultural chemistry and related fields
• Research Institution: Tokyo Metropolitan University
• Principal Investigator: Hanada Satoshi 首都大学東京, 理学研究科, 教授 (10357791)
• Project Period (FY): 2017-06-30 – 2020-03-31
• Keywords: 嫌気的アンモニア酸化 / 酸素非発生型光合成細菌 / バクテリオクロロフィル / 硝化

Outline of Final Research Achievements

Until now, the oxidation of ammonia to nitrous acid and nitric acid has been considered to be a process that progresses in the presence of oxygen by nitrifying bacteria. However, it is possibility that anoxygenic photosynthetic bacteria can use ammonia as an electron donor for their photosynthetic electron transfer in addition to nitrite, but no photosynthetic bacteria capable of anaerobically oxidizing ammonia have been discovered.
In this study, we succeeded in culturing a marine or thermophilic anoxygenic photosynthetic bacterium capable of oxidizing ammonia under anaerobic conditions from natural environments such as the ocean and hot springs. It has not been clarified what the intermediate products associated with the ammonia oxidation in these bacteria are, but it can be said that these are the first culture examples in the world.

Free Research Field

環境微生物学

Academic Significance and Societal Importance of the Research Achievements

廃水処理プロセスの効率化で問題となっている硝化プロセスを、酸素非発生型光合成細菌を使って、革新することが本研究の目的である。従来の硝化（アンモニアから亜硝酸・硝酸への酸化）は硝化細菌によって酸素存在下で進行すると考えられてきた。しかし、酸素非発生型光合成細菌による亜硝酸の嫌気的酸化が発見され、硝化プロセスを効率化する新たなアプローチとして注目され始めた。未だ発見されていないアンモニア酸化できる酸素非発生型光合成細菌を環境中から見出し、光によってコントロール可能な酸素非存在下での硝化・脱窒プロセスを提案することができる。