Pyrite (FeS₂) is the most abundant sulfide mineral on Earth and represents a significant reservoir of reduced iron and sulfur both today and in the geologic past. In modern environments, oxidative transformations of pyrite and other metal sulfides play a key role in terrestrial element partitioning with broad impacts to contaminant mobility and the formation of acid mine drainage systems. Although the role of aerobic micro‐organisms in pyrite oxidation under acidic‐pH conditions is well known, to date there is very little known about the capacity for aerobic micro‐organisms to oxidize pyrite at circumneutral pH. Here, we describe two enrichment cultures, obtained from pyrite‐bearing subsurface sediments, that were capable of sustained cell growth linked to pyrite oxidation and sulfate generation at neutral pH. The cultures were dominated by two Rhizobiales species (Bradyrhizobium sp. and Mesorhizobium sp.) and a Ralstonia species. Shotgun metagenomic sequencing and genome reconstruction indicated the presence of Fe and S oxidation pathways in these organisms, and the presence of a complete Calvin–Benson–Bassham CO₂ fixation system in the Bradyrhizobium sp. Oxidation of pyrite resulted in thin (30–50 nm) coatings of amorphous Fe(III) oxide on the pyrite surface, with no other secondary Fe or S phases detected by electron microscopy or X‐ray absorption spectroscopy. Rates of microbial pyrite oxidation were approximately one order of magnitude higher than abiotic rates. These results demonstrate the ability of aerobic microbial activity to accelerate pyrite oxidation and expand the potential contribution of micro‐organisms to continental sulfide mineral weathering around the time of the Great Oxidation Event to include neutral‐pH environments. In addition, our findings have direct implications for the geochemistry of modern sedimentary environments, including stimulation of the early stages of acid mine drainage formation and mobilization of pyrite‐associated metals.

中文翻译：

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在环境pH值下好氧黄铁矿氧化的微生物加速。

硫铁矿（FeS ₂）是地球上最丰富的硫化物矿物，并且代表了当今和过去地质学中大量还原的铁和硫。在现代环境中，黄铁矿和其他金属硫化物的氧化转化在陆地元素分配中起关键作用，对污染物的迁移和酸性矿山排水系统的形成产生广泛影响。尽管好氧微生物在酸性pH条件下在黄铁矿氧化中的作用是众所周知的，但迄今为止，关于好氧微生物在环境pH下氧化黄铁矿的能力知之甚少。在这里，我们描述了两种富集培养物，它们是从含黄铁矿的地下沉积物中获得的，能够在中性pH下与黄铁矿氧化和硫酸盐生成相关的持续细胞生长。文化由两个主导根瘤菌属物种（Bradyrhizobium sp。和Mesorhizobium sp。）和Ralstonia种。gun弹枪宏基因组测序和基因组重建表明这些生物中存在Fe和S氧化途径，而缓生根瘤菌中存在完整的Calvin–Benson–Bassham CO ₂固定系统sp。黄铁矿的氧化导致在黄铁矿表面上形成无定形的Fe（III）氧化物薄（30–50 nm）涂层，而电子显微镜或X射线吸收光谱法未检测到其他次生Fe或S相。微生物黄铁矿氧化速率比非生物速率高约一个数量级。这些结果表明，有氧微生物活性具有加速黄铁矿氧化并扩展微生物对大氧化事件前后包括中性pH环境的大陆硫化物矿物风化的潜在贡献的能力。此外，我们的发现对现代沉积环境的地球化学有直接影响，包括刺激酸性矿山排水形成的早期阶段以及与黄铁矿相关的金属动员。