Sulfate-reducing bacteria (SRBs) and dissimilatory iron-reducing bacteria (DIRBs) are recognized as significant contributors to the occurrence of elevated arsenic (As) levels in groundwater. However, the precise effects and underlying mechanisms of their interactions on As behavior within sediments remain poorly understood. In this investigation, we compared the impacts and mechanisms of DIRBs, SRBs, and mixed bacterial consortia on the migration behavior of As and Fe/S species. Our findings revealed that during the initial phase of the reaction (0–8 days, Stage 1), the mixed bacterial consortium facilitated As release by intensifying the reduction of Fe (III) and sulfate, resulting in a maximum As concentration 1.5 times higher than that observed with either DIRBs or SRBs in isolation. Subsequently, in the intermediate phase (8–20 days, Stage 2), the mixed consortium suppressed the synthesis of sulfate reductase and the secretion of toxic substances (e.g., o-Methyltoluene) associated with steroid degradation pathways. This inhibition consequently reduced the formation of secondary Fe minerals and the fixation of As. Finally, in the latter stage (20–30 days, Stage 3), the system responded to the threat of toxic substances by secreting significant amounts of organic acids to facilitate their decomposition. However, this process also led to the re-decomposition of iron oxides, resulting in the release of As. These observations shed light on the intricate interplay between DIRBs and SRBs within bacterial consortia, elucidating their coordinated actions in inducing the migration and transformation of arsenic.

中文翻译：

---

硫酸盐还原菌 （SRB） 和异化铁还原菌 （DIRB） 共存对沉积物中砷的运移和转化的影响


硫酸盐还原菌 （SRB） 和异化铁还原菌 （DIRB） 被认为是地下水中砷 （As） 含量升高的重要因素。然而，它们相互作用对沉积物中 As 行为的确切影响和潜在机制仍然知之甚少。在这项研究中，我们比较了 DIRBs、SRBs 和混合细菌联盟对 As 和 Fe/S 物种迁移行为的影响和机制。我们的研究结果表明，在反应的初始阶段（0-8 天，第 1 阶段），混合细菌联盟通过加强 Fe （III） 和硫酸盐的还原来促进 As 的释放，导致最大 As 浓度比单独观察到的 DIRBs 或 SRB 高 1.5 倍。随后，在中间阶段（8-20 天，第 2 阶段），混合联盟抑制了硫酸盐还原酶的合成和与类固醇降解途径相关的有毒物质（例如邻甲基甲苯）的分泌。因此，这种抑制减少了次生 Fe 矿物的形成和 As 的固定。最后，在后期（20-30 天，第 3 阶段），系统通过分泌大量有机酸以促进其分解来应对有毒物质的威胁。然而，这个过程也导致氧化铁的重新分解，导致 As 的释放。这些观察揭示了细菌联盟内 DIRBs 和 SRBs 之间错综复杂的相互作用，阐明了它们在诱导砷迁移和转化方面的协调作用。