Members of the genus Aeromonas prevail in aquatic habitats and have a great potential in biological wastewater treatment because of their unique extracellular electron transfer (EET) capabilities. However, the mediated EET mechanisms of Aeromonas have not been fully understood yet, hindering their applications in biological wastewater treatment processes. In this study, the electron shuttles in Aeromonas hydrophila, a model and widespread strain in aquatic environments and wastewater treatment plants, were explored. A. hydrophila was found to produce both flavins and 2-amino-3-carboxy-1,4-naphthoquinone (ACNQ) as electron shuttles and utilize them to accelerate its EET for the bioreduction of various pollutants. The Mtr-like respiratory pathway was essential for the reduction of flavins, but not involved in the ACNQ reduction. The electron shuttle activity of ACNQ for pollutant bioreduction involved the redox reactions that occurred inside the cell. These findings deepen our understanding about the underlying EET mechanisms in dissimilatory metal reducing bacteria and provide new insights into the roles of the genus Aeromonas in biological wastewater treatment.

中文翻译：

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通过水性嗜水气单胞菌中的多个电子穿梭进行细胞外电子转移，用于污染物的生物还原

气单胞菌属的成员在水生生境中普遍存在，并且由于其独特的细胞外电子转移 (EET) 能力而在生物废水处理方面具有巨大潜力。然而，气单胞菌的介导 EET 机制尚未完全了解，阻碍了它们在生物废水处理过程中的应用。在这项研究中，探索了嗜水气单胞菌中的电子穿梭，这是一种在水生环境和废水处理厂中广泛存在的模型和菌株。A. 嗜水菌被发现产生黄素和 2-氨基-3-羧基-1,4-萘醌 (ACNQ) 作为电子穿梭，并利用它们加速其 EET 以生物还原各种污染物。Mtr 样呼吸通路对于减少黄素是必不可少的，但不参与 ACNQ 的减少。ACNQ 用于污染物生物还原的电子穿梭活性涉及细胞内发生的氧化还原反应。这些发现加深了我们对异化金属还原细菌中潜在 EET 机制的理解，并为气单胞菌属在生物废水处理中的作用提供了新的见解。