Dark matter in nitrification illuminated by cultivation technique and genome analysis: Complete ammonia-oxidizing bacteria

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K16218
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 45030:Biodiversity and systematics-related
• Research Institution: Chuo University (2020-2021); National Institute of Advanced Industrial Science and Technology (2019)
• Principal Investigator: Fujitani Hirotsugu 中央大学, 理工学部, 助教 (50708617)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 硝化 / comammox / 土壌 / 培養 / ゲノム / 酸性 / アンモニア / 亜硝酸

Outline of Final Research Achievements

In this study, we aimed to cultivate complete ammonia oxidation (comammox) Nitrospira, which oxidize ammonia to nitrate in a single cell and characterize their physiological and genomic features. The genus Nitrospira, which occupied 1% in an acidic soil, was enriched up to 92% during incubation. The enriched Nitrospira was able to survive an acidic condition of pH 4 and its genome encoded all the genes for comammox. Furthermore, the genome content was distinct from the previously reported four comammox species. Thus, we successfully cultivated a novel comammox Nitrospira in a viewpoint of physiology and genomics.

Free Research Field

微生物生態学，環境微生物学

Academic Significance and Societal Importance of the Research Achievements

培養の播種源に用いた茶園土壌は，多量の窒素肥料が投入され，活発に硝化が起こる酸性土壌である。硝化を人為的に制御することは，窒素負荷を低減し，温室効果ガスである亜酸化窒素の削減にも貢献する。しかしながら，こうした環境への負荷を及ぼす要因となる，微生物の学術的知見は乏しい。本研究で得られた comammox細菌の知見は，窒素循環に関連する環境負荷を削減するための方策や人為的に硝化を制御するための技術開発の一助となる。