Geobacter

Lovley, Derek R.; Ueki, Toshiyuki; Zhang, Tian; Malvankar, Nikhil S.; Shrestha, Pravin Malla; Flanagan, Kelly A.; Aklujkar, Muktak; Butler, Jessica; Giloteaux, Ludovic; Rotaru, Amelia-Elena; Holmes, Dawn E.; Franks, Ashley E.; Orellana, Roberto; Risso, Carla; Nevin, Kelly P.

doi:10.1016/b978-0-12-387661-4.00004-5

Cited by 578 publications

(295 citation statements)

References 488 publications

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“…MET are anaerobic systems in which microorganisms catalyse oxidation or reduction reactions using solid‐state electrodes, suitably deployed in the contaminated matrix, as virtually inexhaustible electron acceptors or donors, respectively (Aulenta et al ., 2009; Zhang et al ., 2010, 2013; Lovley et al ., 2011; Rodrigo Quejigo et al ., 2016; Lai et al ., 2017). Laboratory‐scale studies have shown that MET can be employed to stimulate the anaerobic oxidation of a variety of reduced contaminants in soil and groundwater, including lower chlorinated compounds and PHs (Daghio et al ., 2017).…”

Section: Introductionmentioning

confidence: 99%

The bioelectric well: a novel approach for in situ treatment of hydrocarbon‐contaminated groundwater

Palma

Daghio

Franzetti

et al. 2017

Microbial Biotechnology

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SummaryGroundwater contamination by petroleum hydrocarbons (PHs) is a widespread problem which poses serious environmental and health concerns. Recently, microbial electrochemical technologies (MET) have attracted considerable attention for remediation applications, having the potential to overcome some of the limiting factors of conventional in situ bioremediation systems. So far, field‐scale application of MET has been largely hindered by the limited availability of scalable system configurations. Here, we describe the ‘bioelectric well’ a bioelectrochemical reactor configuration, which can be installed directly within groundwater wells and can be applied for in situ treatment of organic contaminants, such as PHs. A laboratory‐scale prototype of the bioelectric well has been set up and operated in continuous‐flow regime with phenol as the model contaminant. The best performance was obtained when the system was inoculated with refinery sludge and the anode potentiostatically controlled at +0.2 V versus SHE. Under this condition, the influent phenol (25 mg l−1) was nearly completely (99.5 ± 0.4%) removed, with an average degradation rate of 59 ± 3 mg l−1 d and a coulombic efficiency of 104 ± 4%. Microbial community analysis revealed a remarkable enrichment of Geobacter species on the surface of the graphite anode, clearly pointing to a direct involvement of this electro‐active bacterium in the current‐generating and phenol‐oxidizing process.

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Section: Introductionmentioning

confidence: 99%

The bioelectric well: a novel approach for in situ treatment of hydrocarbon‐contaminated groundwater

Palma

Daghio

Franzetti

et al. 2017

Microbial Biotechnology

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“…[5][6][7] The ability of G. sulfurreducens to produce highly conductive biofilms 9 may be an important factor contributing to its ability to generate high current densities. Although previous studies have speculated that the biofilm conductivity can be attributed to electron hopping between c-type cytochromes, 10,11 this model is inconsistent with multiple lines of evidence, including the temperature-dependence of the biofilm conductivity and the localization of the cytochromes.…”

Section: Introductionmentioning

confidence: 99%

Biofilm conductivity is a decisive variable for high-current-density Geobacter sulfurreducens microbial fuel cells

Malvankar

Tuominen

Lovley

2012

Energy Environ. Sci.

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240

184

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Current outputs of microbial fuel cells (MFCs) are too low for most perceived practical applications. Most efforts for further optimization have focused on modifications of fuel cell architecture or electrode materials, with little investigation into the properties of microorganisms that are most essential for maximal current production. Geobacter sulfurreducens produces the highest current densities of any known pure culture; is closely related to the Geobacter species that often predominate in anode biofilms harvesting electricity from organic wastes; and produces highly conductive anode biofilms. Comparison of biofilm conductivities and current production in different strains of G. sulfurreducens revealed a direct correlation between biofilm conductivity and current density. Electrochemical impedance spectroscopy measurements demonstrated that higher biofilm conductivity not only reduced resistance to electron flow through the biofilm, but also lowered the activation energy barrier for electron transfer between the biofilm and the anode. These results demonstrate the crucial role of biofilm conductivity in achieving high current density in MFCs and suggest that increasing biofilm conductivity can boost MFC performance.

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“…biological electron transfer. 3,5 Long-range electron transport via metallic-like conductivity is likely to have significance for electron transfer to insoluble minerals such as Fe(III) oxides, 6 as well as interspecies electron transfer, 4,7-10 and microbe-electrode electron exchange.…”

Section: Introductionmentioning

confidence: 99%

Lack of cytochrome involvement in long-range electron transport through conductive biofilms and nanowires of Geobacter sulfurreducens

Malvankar

Tuominen

Lovley

2012

Energy Environ. Sci.

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189

166

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Two competing models for long-range electron transport through the conductive biofilms and nanowires of Geobacter sulfurreducens exist. In one model electrons are transported via pili that possess delocalized electronic states to function as protein wires with metallic-like conductivity. In the other model electrons are transported by more traditional electron transfer via electron hopping/tunneling between the c-type cytochromes in G. sulfurreducens biofilms and pili. The cytochrome hypothesis was further examined. Quantifying c-type cytochromes in G. sulfurreducens biofilms and pili indicated that there are insufficient cytochromes to account for electron transport through the bulk of the biofilm or pili and demonstrated that there is a negative correlation between cytochrome abundance and biofilm conductivity. Direct imaging using atomic force microscopy revealed that cytochromes were not packed close enough on pili to permit electron hopping/tunneling along the pili. Inactivating cytochromes had no impact on biofilm conductivity. The results of electrochemical gating studies were inconsistent with electron transport via cytochromes. Theoretical considerations suggest that a cytochrome model cannot explain the previously reported response of biofilm conductivity to temperature changes. These multiple lines of evidence, which rely on approaches with different sets of assumptions, demonstrate that the hypothesis that long-range electron transport through G. sulfurreducens biofilms and nanowires can be attributed to electron hopping/tunneling between c-type cytochromes is incorrect. In contrast, these multiple lines of evidence are consistent with long-range electron transport through the biofilms via networks of pili that possess metallic-like conductivity.

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Geobacter

Cited by 578 publications

References 488 publications

The bioelectric well: a novel approach for in situ treatment of hydrocarbon‐contaminated groundwater

The bioelectric well: a novel approach for in situ treatment of hydrocarbon‐contaminated groundwater

Biofilm conductivity is a decisive variable for high-current-density Geobacter sulfurreducens microbial fuel cells

Lack of cytochrome involvement in long-range electron transport through conductive biofilms and nanowires of Geobacter sulfurreducens

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