共同研究報告書


研究区分 一般研究

研究課題

 Study of novel Fe-oxidizing bacteria
新規・継続の別 新規
研究代表者／所属 海洋研究開発機構
研究代表者／職名 博士研究員
研究代表者／氏名 Jackson Makoto TSUJI

研究分担者／氏名／所属／職名
　
氏　　名
所　　属
職　　名

1

 Masaru K. NOBU 海洋研究開発機構 主任研究員

2

 渡邉友浩 北大低温研

3

 福井学 北大低温研

4

 田中亮一 北大低温研

5

 高林厚史 北大低温研

研究目的 Earth's early oceans were iron-rich and anoxic. How life thrived in such oceans is unclear due to poor knowledge of microbial iron metabolism. To explore ancient iron cycling， here we studied a novel iron-oxidizing photosynthetic bacterium， named strain L227-S17， that was derived from a boreal lake.
　　
研究内容・成果 We performed a cutting-edge biochemical technique (called native PAGE) on strain L227-S17 in FY2024 to separate membrane-bound protein complexes from the strain. Following up on these analyses in FY2025， we performed mass spectrometry on separated fractions to identify proteins that could potentially be involved in photosynthetic iron oxidation. We detected a novel membrane-bound protein across multiple fractions that includes two extracellular heme-binding sites based on in silico predictions. This protein was upregulated in RNA sequencing data from the strain， implying it could play an important role in the strain's metabolism. Future work， such as heterologous expression of the protein and midpoint potential measurements， will clarify the potential role of this protein in photosynthesis or iron oxidation. In addition， we discussed research at the iron-rich alpine wetlands of Oze National Park， where relatives of strain L227-S17 were detected at high relative abundances. Our results provide new insights into the highly novel metabolism of a bacterium that may retain multiple ancestrally derived photosynthetic traits and can help illuminate how Earth’s early ecosystems functioned.
　　
成果となる論文・学会発表等 J. M. Tsuji. Illuminating early Earth's broken iron cycle using a "living fossil" photosynthetic bacterium. University of Waterloo (Canada)， invited seminar presentation. July 23rd， 2025.