Disentangling the roles of free and cytochrome-bound flavins in extracellular electron transport from Shewanella oneidensis MR-1
Disentangling the roles of free and cytochrome-bound flavins in extracellular electron transport from Shewanella oneidensis MR-1
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DOI：
10.1016/j.electacta.2016.03.074
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发表时间：
2016-04-20
影响因子：
6.6
通讯作者：
El-Naggar, Mohamed Y.
中科院分区：
文献类型：
--
作者：
Xu, Shuai;Jangir, Yamini;El-Naggar, Mohamed Y.
除了其自然环境意义外，细胞外电子转移（EET）过程可以在电极界面处利用，以使微生物电化学技术用于可再生能源回收，生物燃料生产，生物修复和废水处理。这些应用的成功取决于更好地理解将电化学活性微生物（如希瓦氏菌MR-1）与电极连接起来的电子转移途径。在这里，我们报告的电化学测量，揭示了黄素依赖性和黄素非依赖性EET途径从S。oneidensis MR-1。值得注意的是，差分脉冲伏安法捕获的氧化还原签名的自由和细胞色素结合的黄素同时在一个实验系统中的第一次，使我们能够比较它们的相对贡献，同时研究细胞去除，黄素，不同的培养条件下，突变破坏黄素分泌的影响。我们的研究结果表明，内源性黄素加速EET从希瓦氏菌到高表面积碳布电极主要作为细胞色素结合的辅因子，而不是游离的可溶性穿梭，从而支持希瓦氏菌EET的两个有争议的模型之一。我们的测量还突出了不同电极材料对微生物氧化还原特征检测的影响程度。这份报告激发了额外的结构研究，研究结合的位置和精确的相互作用，黄素在细胞色素电极接口。(C)2016爱思唯尔有限公司版权所有
In addition to its natural environmental significance, the process of extracellular electron transfer (EET) can be exploited at electrode interfaces to enable microbial electrochemical technologies for renewable energy recovery, biofuel production, bioremediation, and wastewater treatment. Success in these applications hinges on a better understanding of the electron transfer pathways that link electrochemically active microbes, such as Shewanella oneidensis MR-1, to electrodes. Here, we report electrochemical measurements that reveal both flavin-dependent and flavin-independent EET pathways from S. oneidensis MR-1. Significantly, differential pulse voltammetry captured the redox signatures of both free and cytochrome-bound flavins simultaneously in one experimental system for the first time, allowing us to compare their relative contributions while studying the impact of cell-removal, flavin addition, different culture conditions, and a mutant disrupted in flavin secretion. Our results indicate that endogenous flavins accelerate EET from Shewanella to high surface area carbon cloth electrodes primarily as cytochrome-bound cofactors, rather than free soluble shuttles, thereby supporting one of the two debated models of Shewanella EET. Our measurements also highlight the extent to which different electrode materials can impact detection of microbial redox signatures. This report motivates additional structural studies to study the binding location and precise interaction of flavins at cytochrome-electrode interfaces. (C) 2016 Elsevier Ltd. All rights reserved.