Electron transfer from a solid-state electrode assisted by methyl viologen sustains efficient microbial reductive dechlorination of TCE
Electron transfer from a solid-state electrode assisted by methyl viologen sustains efficient microbial reductive dechlorination of TCE
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DOI：
10.1021/es0624321
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发表时间：
2007-04-01
影响因子：
11.4
通讯作者：
Rossetti, Simona
中科院分区：
文献类型：
--
作者：
Aulenta, Federico;Catervi, Alessandro;Rossetti, Simona
通过细胞外途径将电子转移到固体表面的能力通常被微生物利用，这些微生物使用不溶性电子受体，如铁或锰的氧化物或微生物燃料电池中的惰性电极。相反的过程，即在微生物呼吸中使用固体表面或电极作为电子供体，虽然在很大程度上尚未开发，但可能具有重要的环境应用，特别是在从受污染的地下水或废物流中去除氧化污染物方面。在这里，我们首次展示了在-500 mV（相对于标准氢电极）极化的固态电极的电化学电池，结合低电位氧化还原介质（甲基紫素），可以有效地将电化学还原当量传递给使用氯化溶剂呼吸的微生物。通过这种方法，可以将三氯乙烯（一种有毒但常见的地下水污染物）还原转化为无害的最终产品，如乙烯和乙烷。此外，使用甲基viologen修饰的电极，我们甚至可以证明脱氯细菌能够直接从修饰的电极表面接受还原等量物。这个创新的概念，基于通过使用固态电极刺激脱氯反应（我们建议这个过程的缩写为BEARD：生物电化学辅助还原脱氯），有望对氯化溶剂污染的地下水进行原位生物修复，并且与基于地下注入有机化合物的传统方法相比，具有几个潜在的优势。这项研究的结果提出了一种可能性，即固定所选的氧化还原介质可能是一种通用策略，用于刺激和控制一系列使用不溶性电极作为电子供体的微生物反应。
The ability to transfer electrons, via an extracellular path, to solid surfaces is typically exploited by microorganisms which use insoluble electron acceptors, such as iron- or manganese-oxides or inert electrodes in microbial fuel cells. The reverse process, i.e., the use of solid surfaces or electrodes as electron donors in microbial respirations, although largely unexplored, could potentially have important environmental applications, particularly for the removal of oxidized pollutants from contaminated groundwater or waste streams. Here we show, for the first time, that an electrochemical cell with a solid-state electrode polarized at -500 mV (vs standard hydrogen electrode), in combination with a low-potential redox mediator (methyl viologen), can efficiently transfer electrochemical reducing equivalents to microorganisms which respire using chlorinated solvents. By this approach, the reductive transformation of trichloroethene, a toxic yet common groundwater contaminant, to harmless end-products such as ethene and ethane could be performed. Furthermore, using a methyl-viologen-modified electrode we could even demonstrate that dechlorinating bacteria were able to accept reducing equivalents directly from the modified electrode surface. The innovative concept, based on the stimulation of dechlorination reactions through the use of solid-state electrodes (we propose for this process the acronym BEARD: Bio-Electrochemically Assisted Reductive Dechlorination), holds promise for in situ bioremediation of chlorinated-solvent-contaminated groundwater, and has several potential advantages over traditional approaches based on the subsurface injection of organic compounds. The results of this study raise the possibility that immobilization of selected redox mediators may be a general strategy for stimulating and controlling a range of microbial reactions using insoluble electrodes as electron donors.