Elucidation of branched-electron transport chain in iodate-respiring bacteria

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02896
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 38020:Applied microbiology-related
• Research Institution: Chiba University
• Principal Investigator: Amachi Seigo 千葉大学, 大学院園芸学研究院, 教授 (80323393)
• Co-Investigator(Kenkyū-buntansha): 山村 茂樹 国立研究開発法人国立環境研究所, 地域環境保全領域, 室長 (90414391)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: ヨウ素酸呼吸 / 電子伝達鎖 / idr遺伝子 / 放射性ヨウ素 / 地下水汚染 / 銀担持ゼオライト / バイオレメディエーション

Outline of Final Research Achievements

Several types of gene knockout mutants were constructed from an iodate-respiring bacterium Pseudomonas sp. SCT, and their growth under iodate-respring, denitrifying, and oxygen-respiring conditions was compared with that of the wild-type strain. By using one of these mutants, effect of iodate and iodide concentrations on the transcription of idr gene was determined. Idr protein complex was purified, and its molecular weight and subunit composition were deduced. Furthermore, silver-impregnated zeolite was added to the spent medium of Azoarcus sp. DN11, another iodate-respiring bacterium isolated from gasoline-contaminated subsurface aquifer. Iodine was successfully removed from the aqueous phase and recovered as silver iodide (AgI). These results suggest that iodate-respiring bacteria are potentially helpful for bioaugmentation of radioiodine (I-129)-contaminated subsurface aquifers.

Free Research Field

環境微生物学

Academic Significance and Societal Importance of the Research Achievements

ヨウ素酸呼吸は最近になって発見された細菌の嫌気呼吸様式で、脊椎動物の必須元素であるヨウ素の地球規模での循環に与える影響から注目を集めている。またヨウ素酸呼吸細菌は、地下水汚染が報告されている放射性ヨウ素（I-129）の回収・除去にも応用が期待される。本研究では2種類のヨウ素呼吸細菌を用いて、ヨウ素酸呼吸に重要な役割を演じる複数の遺伝子を同定し、その機能を予測した。また、ヨウ素酸呼吸反応を触媒するタンパク質の分子量とサブユニット構造を予測した。さらに、ヨウ素酸呼吸細菌を用いてヨウ素酸をヨウ化物に変換することで、I-129をヨウ化銀（AgI）として効率的に回収・除去できることを示すデータを得た。