<i>Geobacter sulfurreducens</i>
            Can Grow with Oxygen as a Terminal Electron Acceptor

Lin, Winston; Coppi, Maddalena V.; Lovley, Derek R.

doi:10.1128/aem.70.4.2525-2528.2004

Cited by 200 publications

(143 citation statements)

References 32 publications

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“…Fluorescence was measured in two biological replicates, with two technical replicates each, using a SpectraMax M5 plate reader (Molecular Devices) with an excitation of 490 nm and emission of 520 nm. Cell viability after U exposure in comparison with controls without U was assayed by recovering the resting cells in NB medium with acetate and fumarate (NBAF) and measuring the length of the lag phase, as described previously (54). Before inoculation, resting-cell suspensions were gassed for 15 min with filter-sterilized air to reoxidize the U deposits (13) without compromising G. sulfurreducens viability (54).…”

Section: Methodsmentioning

confidence: 99%

“…Cell viability after U exposure in comparison with controls without U was assayed by recovering the resting cells in NB medium with acetate and fumarate (NBAF) and measuring the length of the lag phase, as described previously (54). Before inoculation, resting-cell suspensions were gassed for 15 min with filter-sterilized air to reoxidize the U deposits (13) without compromising G. sulfurreducens viability (54). Cells were harvested by centrifugation (1,200 × g, 5 min), resuspended in 1 mL of wash buffer (final OD 600 of 0.4), and mixed with 10 mL of NBAF in pressure tubes.…”

Section: Methodsmentioning

confidence: 99%

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Extracellular reduction of uranium via Geobacter conductive pili as a protective cellular mechanism

Cologgi

Lampa-Pastirk

Speers

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

218

239

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The in situ stimulation of Fe(III) oxide reduction by Geobacter bacteria leads to the concomitant precipitation of hexavalent uranium [U(VI)] from groundwater. Despite its promise for the bioremediation of uranium contaminants, the biological mechanism behind this reaction remains elusive. Because Fe(III) oxide reduction requires the expression of Geobacter 's conductive pili, we evaluated their contribution to uranium reduction in Geobacter sulfurreducens grown under pili-inducing or noninducing conditions. A pilin-deficient mutant and a genetically complemented strain with reduced outer membrane c -cytochrome content were used as controls. Pili expression significantly enhanced the rate and extent of uranium immobilization per cell and prevented periplasmic mineralization. As a result, pili expression also preserved the vital respiratory activities of the cell envelope and the cell's viability. Uranium preferentially precipitated along the pili and, to a lesser extent, on outer membrane redox-active foci. In contrast, the pilus-defective strains had different degrees of periplasmic mineralization matching well with their outer membrane c -cytochrome content. X-ray absorption spectroscopy analyses demonstrated the extracellular reduction of U(VI) by the pili to mononuclear tetravalent uranium U(IV) complexed by carbon-containing ligands, consistent with a biological reduction. In contrast, the U(IV) in the pilin-deficient mutant cells also required an additional phosphorous ligand, in agreement with the predominantly periplasmic mineralization of uranium observed in this strain. These findings demonstrate a previously unrecognized role for Geobacter conductive pili in the extracellular reduction of uranium, and highlight its essential function as a catalytic and protective cellular mechanism that is of interest for the bioremediation of uranium-contaminated groundwater.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Extracellular reduction of uranium via Geobacter conductive pili as a protective cellular mechanism

Cologgi

Lampa-Pastirk

Speers

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

218

239

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“…Although Geobacter sulfurreducens is often wrongly classified as a strict anaerobe, it has been reported to respire oxygen when supplied at low concentrations (10%) [54], so oxygen could act as a true electrode competitor for accepting electrons from microbial metabolism. In addition to this physiological role, oxygen may also be toxic over certain levels by oxidizing the cytochrome network and blocking the electron transfer.…”

Section: Microbial Electrolysis Cells Performance With Real Wastewatermentioning

confidence: 99%

Strategies for Reducing the Start-up Operation of Microbial Electrochemical Treatments of Urban Wastewater

et al. 2015

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Abstract:Microbial electrochemical technologies (METs) constitute the core of a number of emerging technologies with a high potential for treating urban wastewater due to a fascinating reaction mechanism-the electron transfer between bacteria and electrodes to transform metabolism into electrical current. In the current work, we focus on the model electroactive microorganism Geobacter sulfurreducens to explore both the design of new start-up procedures and electrochemical operations. Our chemostat-grown plug and play cells, were able to reduce the start-up period by 20-fold while enhancing chemical oxygen demand (COD) removal by more than 6-fold during this period. Moreover, a filter-press based bioreactor was successfully tested for both acetate-supplemented synthetic wastewater and real urban wastewater. This proof-of-concept pre-pilot treatment included a microbial electrolysis cell (MEC) followed in time by a microbial fuel cell (MFC) to finally generate electrical current of ca. 20 A¨m´2 with a power of 10 W¨m´2 while removing 42 g COD day´1¨m´2.The effective removal of acetate suggests a potential use of this modular technology for treating acetogenic wastewater where Geobacter sulfurreducens outcompetes other organisms.

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“…There is a broad range of requirements and tolerances toward oxygen among microorganisms between the strictly anaerobic and fully aerobic bacteria. Some anaerobic microbes do not tolerate any level of oxygen; others tolerate various concentrations and have different levels of inhi-bition (42,135). Other bacteria require oxygen for their energy metabolism but are extremely sensitive to higher oxygen concentrations (139,161).…”

Section: Why Are Most Bacteria Currentlymentioning

confidence: 99%

Central Role of the Cell in Microbial Ecology

Zengler

2009

Microbiol Mol Biol Rev

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SUMMARY Over the last few decades, advances in cultivation-independent methods have significantly contributed to our understanding of microbial diversity and community composition in the environment. At the same time, cultivation-dependent methods have thrived, and the growing number of organisms obtained thereby have allowed for detailed studies of their physiology and genetics. Still, most microorganisms are recalcitrant to cultivation. This review not only conveys current knowledge about different isolation and cultivation strategies but also discusses what implications can be drawn from pure culture work for studies in microbial ecology. Specifically, in the light of single-cell individuality and genome heterogeneity, it becomes important to evaluate population-wide measurements carefully. An overview of various approaches in microbial ecology is given, and the cell as a central unit for understanding processes on a community level is discussed.

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Geobacter sulfurreducens Can Grow with Oxygen as a Terminal Electron Acceptor

Cited by 200 publications

References 32 publications

Extracellular reduction of uranium via Geobacter conductive pili as a protective cellular mechanism

Extracellular reduction of uranium via Geobacter conductive pili as a protective cellular mechanism

Strategies for Reducing the Start-up Operation of Microbial Electrochemical Treatments of Urban Wastewater

Central Role of the Cell in Microbial Ecology

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