Direct electron uptake is emerging as a key process for electron transfer in anaerobic microbial communities, both between species and from extracellular sources, such as zero‐valent iron (Fe⁰) or cathodic surfaces. In this study, we investigated cathodic electron uptake by Fe⁰‐corroding Desulfovibrio ferrophilus IS5 and showed that electron uptake is dependent on direct cell contact via a biofilm on the cathode surface rather than through secreted intermediates. Induction of cathodic electron uptake by lactate‐starved D. ferrophilus IS5 cells resulted in the expression of all components necessary for electron uptake; however, protein synthesis was required for full biofilm formation. Notably, proteinase K treatment uncoupled electron uptake from biofilm formation, likely through proteolytic degradation of proteinaceous components of the electron uptake machinery. We also showed that cathodic electron uptake is dependent on SO₄²⁻ reduction. The insensitivity of Fe⁰ corrosion to proteinase K treatment suggests that electron uptake from a cathode might involve different mechanism(s) than those involved in Fe⁰ corrosion.

中文翻译：

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直接阴极电子摄取与硫酸铁的脱硫脱硫弧菌IS5生物膜结合。

在厌氧微生物群落中，无论是物种间还是来自细胞外源（例如零价铁（Fe ⁰）或阴极表面）的直接电子吸收，都已成为电子转移的关键过程。在这项研究中，我们调查了腐蚀Fe ^0的Desulfovibrio ferrophilus IS5对阴极电子的吸收，并表明电子的吸收取决于细胞通过阴极表面的生物膜而不是通过分泌的中间体直接接触。乳酸饥饿的嗜铁衣藻诱导阴极电子摄取IS5细胞导致电子摄取所必需的所有成分的表达。但是，蛋白质合成是完整生物膜形成所必需的。值得注意的是，蛋白酶K处理可能通过电子吸收机制中蛋白质成分的蛋白水解降解，使生物膜形成中的电子吸收解耦。我们还表明，阴极电子的吸收取决于SO ₄ ^2-的还原。Fe ⁰腐蚀对蛋白酶K处理的不敏感性表明，从阴极吸收电子可能与Fe ⁰腐蚀所涉及的机制不同。