Abstract Microbiological Fe(III) reduction under oxic and acidic conditions in acid mine drainage (AMD)-impacted systems is surprising, given the greater energetic favorability of O2 reduction than Fe(III) reduction. A possible explanation for this observation is that the energetic favorability of Fe(III) reduction approaches that of O2 reduction at pH < ∼2. However, some microorganisms require O2 for optimal Fe(III) reduction, and the process has still been observed at pH ≥ 3.5 under oxic conditions. We set up acidophilic Fe(III) reducing enrichment cultures with and without O2. The time of initiation and extent of Fe(III) reduction in oxic and anoxic enrichments were identical, and Fe(III) reduction by the enrichment cultures occurred to similar extents with subsequent transfers of the cultures. Desulfosporosinus- and Clostridia-attributable phylotypes dominated the anoxic enrichment cultures and Alicyclobacillus- and Acidibacillus-attributable phylotypes dominated the oxic enrichment cultures. Our results indicate that while O2 does not impact Fe(III)-reducing activities, it does impact the types of organisms that can be enriched in its presence or absence. The ability of AMD-associated organisms to reduce Fe(III) under both oxic and anoxic conditions may allow them to adapt to fluctuating O2 levels that are encountered in AMD-impacted settings.

中文翻译：

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O2对嗜酸性Fe(III)还原菌富集和活性的影响

摘要 在酸性矿山排水 (AMD) 影响的系统中，在有氧和酸性条件下微生物 Fe(III) 还原是令人惊讶的，因为 O2 还原比 Fe(III) 还原具有更大的能量有利性。对这一观察结果的一个可能解释是，Fe(III) 还原的能量有利性接近于 pH < 2 时 O2 还原的能量有利性。然而，一些微生物需要 O2 来实现最佳的 Fe(III) 还原，并且在 pH ≥ 3.5 的有氧条件下仍然观察到该过程。我们建立了有和没有 O2 的嗜酸性 Fe(III) 还原富集培养物。Fe(III) 在好氧和缺氧富集中的起始时间和还原程度相同，富集培养物对 Fe(III) 的还原程度与随后的培养物转移相似。Desulfosporosinus 和梭菌属的系统发育型在缺氧富集培养物中占主导地位，而脂环酸杆菌和酸杆菌属的系统发育型在有氧富集培养物中占主导地位。我们的结果表明，虽然 O2 不会影响 Fe(III) 还原活性，但它确实会影响在其存在或不存在时可以富集的生物体类型。AMD 相关生物在有氧和缺氧条件下还原 Fe(III) 的能力可能使它们能够适应 AMD 影响环境中遇到的波动的 O2 水平。它确实会影响在其存在或不存在时可以富集的生物体类型。AMD 相关生物在有氧和缺氧条件下还原 Fe(III) 的能力可能使它们能够适应 AMD 影响环境中遇到的波动的 O2 水平。它确实会影响在其存在或不存在时可以富集的生物体类型。AMD 相关生物在有氧和缺氧条件下还原 Fe(III) 的能力可能使它们能够适应 AMD 影响环境中遇到的波动的 O2 水平。