Characteristics and community dynamics of microaerophilic iron-oxidizing bacteria in paddy field soil

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K05372
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38010:Plant nutrition and soil science-related
• Research Institution: Nagoya University
• Principal Investigator: Watanabe Takeshi 名古屋大学, 生命農学研究科, 講師 (60547016)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 水田 / 鉄 / 鉄酸化細菌

Outline of Final Research Achievements

The characteristics of Fe oxides formed during the growth of Gallionella-related Fe-oxidizing bacteria and dynamics of Gallionella-related Fe-oxidizing bacterial community in paddy field soils were studied to understand the role and significance of them in the Fe oxidizing process in paddy field soil. The microscopic observations and XAFS analysis showed that Gallionella-related Fe-oxidizing bacteria produced ferrihydrite-predominated iron oxides during the growth, some of which produce dendrite structures of Fe oxides. The community analysis showed that the dynamics of Gallionella-related Fe-oxidizing bacterial community changed depending on the redox cycle of Fe in paddy soils. These results suggested that Gallionella-related Fe-oxidizing bacteria are involved in the Fe-oxidizing process in paddy field soil, and their behavior may influence the dynamics of not only Fe but also other elements in the soil.

Free Research Field

土壌微生物学

Academic Significance and Societal Importance of the Research Achievements

鉄の酸化還元反応は、水田土壌の物質代謝において重要な役割を担う。このうち、鉄の酸化反応については、これまで非生物的反応(いわゆる空気酸化)が主体と考えられ、鉄酸化細菌による生物的反応については知見が限られていた。本研究では、Gallionellaceae科の微好気性鉄酸化細菌に注目し、土壌中での鉄酸化過程に微好気性鉄酸化細菌が関与していることを初めて示した。また、非生物的な反応による鉄酸化物とは異なる特徴的な形態の鉄酸化物が一部形成されることを示した。これらの成果は、水田土壌の物質代謝のさらなる理解につながると期待され、環境や食の安全に配慮した持続可能な水稲栽培管理の確立に役立つと考えられる。