Electron Transfer from a Solid-State Electrode Assisted by Methyl Viologen Sustains Efficient Microbial Reductive Dechlorination of TCE

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• 作者：Federico Aulenta ; Alessandro Catervi ; Mauro Majone ; Stefania Panero ; Priscilla Reale ; Simona Rossetti
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：April 1, 2007
• 年：2007
• 卷：41
• 期：7
• 页码：2554 - 2559
• 全文大小：347K
• 年卷期：v.41,no.7(April 1, 2007)
• ISSN：1520-5851

文摘

The ability to transfer electrons, via an extracellular path,to solid surfaces is typically exploited by microorganismswhich use insoluble electron acceptors, such as iron-or manganese-oxides or inert electrodes in microbial fuelcells. The reverse process, i.e., the use of solid surfacesor electrodes as electron donors in microbial respirations,although largely unexplored, could potentially haveimportant environmental applications, particularly for theremoval of oxidized pollutants from contaminated groundwateror waste streams. Here we show, for the first time, thatan electrochemical cell with a solid-state electrode polarizedat -500 mV (vs standard hydrogen electrode), incombination with a low-potential redox mediator (methylviologen), can efficiently transfer electrochemical reducingequivalents to microorganisms which respire usingchlorinated solvents. By this approach, the reductivetransformation of trichloroethene, a toxic yet commongroundwater contaminant, to harmless end-products suchas ethene and ethane could be performed. Furthermore,using a methyl-viologen-modified electrode we could evendemonstrate that dechlorinating bacteria were able toaccept reducing equivalents directly from the modifiedelectrode surface. The innovative concept, based on thestimulation of dechlorination reactions through the use of solid-state electrodes (we propose for this process the acronymBEARD: Bio-Electrochemically Assisted ReductiveDechlorination), holds promise for in situ bioremediationof chlorinated-solvent-contaminated groundwater, and hasseveral potential advantages over traditional approachesbased on the subsurface injection of organic compounds.The results of this study raise the possibility that immobilization of selected redox mediators may be a generalstrategy for stimulating and controlling a range of microbialreactions using insoluble electrodes as electron donors.