Electrochemical Stimulation of Microbial Perchlorate Reduction

Thrash, J. Cameron; Trump, J. Ian Van; Weber, Karrie A.; Miller, E; Achenbach, Laurie A.; Coates, John D.

doi:10.1021/es062772m

Cited by 203 publications

(120 citation statements)

References 39 publications

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“…Cations make up the charge balance by diffusing from anode to cathode through a charge-selective separator (Rabaey and Verstraete, 2005). In addition, bacteria can consume electrons at the cathode with the reduction of electrochemically positive electron acceptors such as nitrate, perchlorate or metals (Gregory et al, 2004;Gregory and Lovley, 2005;Clauwaert et al, 2007;Thrash et al, 2007).…”

Section: From Extracellular Electron Transfer To Bio-electrochemical mentioning

confidence: 99%

“…Recently, also the reduction of perchlorate in the cathode compartment of a BES was described. Thrash et al (2007) were able to isolate one of the organisms responsible for the perchlorate reduction, which was designated strain VDY. When the cathode potential was poised at À500 mV vs Ag/AgCl reference, the organism was capable of reducing perchlorate without the addition of a redox mediator.…”

Section: Reductive Processesmentioning

confidence: 99%

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Microbial ecology meets electrochemistry: electricity-driven and driving communities

et al. 2007

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Bio-electrochemical systems (BESs) have recently emerged as an exciting technology. In a BES, bacteria interact with electrodes using electrons, which are either removed or supplied through an electrical circuit. The most-described type of BES is microbial fuel cells (MFCs), in which useful power is generated from electron donors as, for example, present in wastewater. This form of charge transport, known as extracellular electron transfer, was previously extensively described with respect to metals such as iron and manganese. The importance of these interactions in global biogeochemical cycles is essentially undisputed. A wide variety of bacteria can participate in extracellular electron transfer, and this phenomenon is far more widespread than previously thought. The use of BESs in diverse research projects is helping elucidate the mechanism by which bacteria shuttle electrons externally. New forms of interactions between bacteria have been discovered demonstrating how multiple populations within microbial communities can co-operate to achieve energy generation. New environmental processes that were difficult to observe or study previously can now be simulated and improved via BESs. Whereas pure culture studies make up the majority of the studies performed thus far, even greater contributions of BESs are expected to occur in natural environments and with mixed microbial communities. Owing to their versatility, unmatched level of control and capacity to sustain novel processes, BESs might well serve as the foundation of a new environmental biotechnology. While highlighting some of the major breakthroughs and addressing only recently obtained data, this review points out that despite rapid progress, many questions remain unanswered.

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Section: From Extracellular Electron Transfer To Bio-electrochemical mentioning

confidence: 99%

Section: Reductive Processesmentioning

confidence: 99%

Microbial ecology meets electrochemistry: electricity-driven and driving communities

et al. 2007

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“…When net electrical energy is obtained from a BES, the system is referred to as a microbial fuel cell (MFC). This technology includes anodic reactions where electron donors, such as organic compounds and sulfide, are oxidized, and cathodic reactions where electron acceptors, such as oxygen, nitrate, nitrite or perchlorate, are reduced (Clauwaert et al, 2007;Rabaey et al, 2008;Thrash et al, 2007;Virdis et al, 2008). Anodic and cathodic reactions can be coupled so that the anodic oxidation reaction generates sufficient power for cathodic reduction reactions to occur.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, it is likely that bacteria reducing nitrate at cathodes powered by anodic reactions access electrons from the cathode and not through hydrogen. Our current knowledge of bacterial denitrification reactions relevant to BES cathodes is based on pure-culture studies of chemolithotrophic denitrification coupled to inorganic electron donors (Fernández et al, 2008;Weber et al, 2006) and cathodes as electron donors for anaerobic respiration (Gregory et al, 2004;Thrash et al, 2007;Strycharz et al, 2008;Thrash and Coates, 2008;He et al, 2009). Presently, only two studies examined microbial biofilm communities in denitrifying BESs (Gregory et al, 2004;Park et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Bacterial community structure corresponds to performance during cathodic nitrate reduction

et al. 2010

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Microbial fuel cells (MFCs) have applications other than electricity production, including the capacity to power desirable reactions in the cathode chamber. However, current knowledge of the microbial ecology and physiology of biocathodes is minimal, and as a result more research dedicated to understanding the microbial communities active in cathode biofilms is required. Here we characterize the microbiology of denitrifying bacterial communities stimulated by reducing equivalents generated from the anodic oxidation of acetate. We analyzed biofilms isolated from two types of cathodic denitrification systems: (1) a loop format where the effluent from the carbon oxidation step in the anode is subjected to a nitrifying reactor which is fed to the cathode chamber and (2) an alternative non-loop format where anodic and cathodic feed streams are separated. The results of our study indicate the superior performance of the loop reactor in terms of enhanced current production and nitrate removal rates. We hypothesized that phylogenetic or structural features of the microbial communities could explain the increased performance of the loop reactor. We used PhyloChip with 16S rRNA (cDNA) and fluorescent in situ hybridization to characterize the active bacterial communities. Our study results reveal a greater richness, as well as an increased phylogenetic diversity, active in denitrifying biofilms than was previously identified in cathodic systems. Specifically, we identified Proteobacteria, Firmicutes and Chloroflexi members that were dominant in denitrifying cathodes. In addition, our study results indicate that it is the structural component, in terms of bacterial richness and evenness, rather than the phylogenetic affiliation of dominant bacteria, that best corresponds to cathode performance.

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“…But how bacteria take in electrons from insoluble donors has not been established yet, despite a rapidly increasing number of studies on biocatalyzed cathodes (Bergel et al, 2005;He and Angenent, 2006). In two studies on cathode-driven bacterial reduction, low cathodic potentials were applied at which hydrogen gas could evolve at the cathode (Gregory et al, 2004;Thrash et al, 2007). However, the capacity by a hydrogen uptake deficient Geobacter strain to receive electrons indicates that direct transfer may be possible (Gregory et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Cathodic oxygen reduction catalyzed by bacteria in microbial fuel cells

et al. 2008

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Microbial fuel cells (MFCs) have the potential to combine wastewater treatment efficiency with energetic efficiency. One of the major impediments to MFC implementation is the operation of the cathode compartment, as it employs environmentally unfriendly catalysts such as platinum. As recently shown, bacteria can facilitate sustainable and cost-effective cathode catalysis for nitrate and also oxygen. Here we describe a carbon cathode open to the air, on which attached bacteria catalyzed oxygen reduction. The bacteria present were able to reduce oxygen as the ultimate electron acceptor using electrons provided by the solid-phase cathode. Current densities of up to 2.2 A m À2 cathode projected surface were obtained (0.303±0.017 W m À2 , 15W m À3 total reactor volume). The cathodic microbial community was dominated by Sphingobacterium, Acinetobacter and Acidovorax sp., according to 16S rRNA gene clone library analysis. Isolates of Sphingobacterium sp. and Acinetobacter sp. were obtained using H 2 /O 2 mixtures. Some of the pure culture isolates obtained from the cathode showed an increase in the power output of up to three-fold compared to a non-inoculated control, that is, from 0.015 ± 0.001 to 0.049 ± 0.025 W m À2 cathode projected surface. The strong decrease in activation losses indicates that bacteria function as true catalysts for oxygen reduction. Owing to the high overpotential for non-catalyzed reduction, oxygen is only to a limited extent competitive toward the electron donor, that is, the cathode. Further research to refine the operational parameters and increase the current density by modifying the electrode surface and elucidating the bacterial metabolism is warranted.

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Electrochemical Stimulation of Microbial Perchlorate Reduction

Cited by 203 publications

References 39 publications

Microbial ecology meets electrochemistry: electricity-driven and driving communities

Microbial ecology meets electrochemistry: electricity-driven and driving communities

Bacterial community structure corresponds to performance during cathodic nitrate reduction

Cathodic oxygen reduction catalyzed by bacteria in microbial fuel cells

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