硫化物酸化と鉄還元を結びつける微生物プロセスを発見(Scientists uncover hidden microbial process linking sulfur and iron)

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2025-09-10 浙江大学(ZJU)

浙江大学環境資源科学学院の陳松燦教授らは、硫化物酸化と鉄還元を結びつける新たな微生物代謝プロセスを発見した。従来、硫化物は酸素や硝酸塩など既知の酸化剤がない環境でも硫酸に再酸化されることが知られていたが、その仕組みは不明だった。研究チームはゲノム解析で硫黄酸化と鉄還元に関わる遺伝子が複数の微生物系統に共存することを確認。モデル菌種Desulfurivibrio alkaliphilusを用いた安定同位体追跡やナノスケール二次イオン質量分析により、鉄酸化物を電子受容体として硫化物を完全に酸化し増殖することを実証した。さらに低濃度硫化物条件下でもこの反応を行い、電子伝達に多へムシトクロムを利用することが判明。類縁種は海洋堆積物や熱水噴出孔、湿地などに広く存在し、無酸素・鉄豊富な環境における硫黄―鉄結合サイクルの普遍性が示唆された。

硫化物酸化と鉄還元を結びつける微生物プロセスを発見(Scientists uncover hidden microbial process linking sulfur and iron)

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硫化物酸化と結合した微生物の鉄酸化物呼吸 Microbial iron oxide respiration coupled to sulfide oxidation

Song-Can Chen,Xiao-Min Li,Nicola Battisti,Guoqing Guan,Maria A. Montoya,Jay Osvatic,Petra Pjevac,Shaul Pollak,Andreas Richter,Arno Schintlmeister,Wolfgang Wanek,Marc Mussmann & Alexander Loy
Nature  Published:27 August 2025
DOI:https://doi.org/10.1038/s41586-025-09467-0

Abstract

Microorganisms have driven Earth’s sulfur cycle since the emergence of life1,2,3,4,5,6, yet the sulfur-cycling capacities of microorganisms and their integration with other element cycles remain incompletely understood. One such uncharacterized metabolism is the coupling of sulfide oxidation with iron(iii) oxide reduction, a ubiquitous environmental process hitherto considered to be strictly abiotic7,8. Here we present a comprehensive genomic analysis of sulfur metabolism across prokaryotes, and reveal bacteria that are capable of oxidizing sulfide using extracellular solid phase iron(iii). Based on a phylogenetic framework of over hundred genes involved in dissimilatory transformation of sulfur compounds, we recorded sulfur-cycling capacity in most bacterial and archaeal phyla. Metabolic reconstructions predicted co-occurrence of sulfur compound oxidation and iron(iii) oxide respiration in diverse members of 37 prokaryotic phyla. Physiological and transcriptomic evidence demonstrated that a cultivated representative, Desulfurivibrio alkaliphilus, grows autotrophically by oxidizing dissolved sulfide or iron monosulfide (FeS) to sulfate with ferrihydrite as an extracellular iron(iii) electron acceptor. The biological process outpaced the abiotic process at environmentally relevant sulfide concentrations. These findings expand the known diversity of sulfur-cycling microorganisms and unveil a biological mechanism that links sulfur and iron cycling in anoxic environments, thus highlighting the fundamental role of microorganisms in global element cycles.

生物環境工学
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