Pyrite autotrophic denitrification (PAD) represents an important natural attenuation process of nitrate pollution and plays a pivotal role in linking nitrogen, sulfur, and iron cycles in a variety of anoxic environments. However, there are knowledge gaps about the oxidation mechanism of pyrite under anaerobic neutral conditions. This study explored the performance of PAD in the presence of EDTA and revealed the mechanism of anaerobic pyrite oxidation and microbial mineral transformation. It was demonstrated that ~200 mV was the electrochemical threshold for converting pyrite into bioavailable forms in PAD conditions, and accelerated pyrite oxidation by Fe³⁺-EDTA complexes can improve the performance of PAD effectively. Furthermore, genus related to sulfur and nitrogen cycle (Sulfurimonas, Denitrobacter) were found at higher abundances in cultures containing EDTA. The analysis of metagenomic binning showed that the microbial community in PAD culture with EDTA addition exhibited higher levels of functional diversity and redundancy. These results will further the understanding of the oxidation mechanism of pyrite under anaerobic neutral conditions and the corresponding microbial activities, and provide insights into the practical application of PAD.

硫铁矿自养反硝化（PAD）代表着硝酸盐污染的重要自然衰减过程，并且在各种缺氧环境中，在连接氮，硫和铁循环方面起着关键作用。然而，在厌氧中性条件下黄铁矿的氧化机理存在知识空白。这项研究探索了在EDTA存在下PAD的性能，并揭示了厌氧黄铁矿氧化和微生物矿物转化的机理。结果表明，〜200 mV是在PAD条件下将黄铁矿转化为生物可利用形式的电化学阈值，Fe ³⁺ -EDTA配合物加速黄铁矿氧化可有效提高PAD的性能。此外，属与硫和氮循环（Sulfurimonas在含有EDTA的培养物中发现了较高的丰度（Denitrobacter）。宏基因组分级的分析表明，添加EDTA的PAD培养中的微生物群落具有较高的功能多样性和冗余度。这些结果将进一步了解黄铁矿在厌氧中性条件下的氧化机理以及相应的微生物活性，并为PAD的实际应用提供见识。