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Acetate Oxidation Coupled To Fe(Iii) Reduction In Hyperthermophilic Microorganisms, Jason M. Tor, Kazem Kashefi, Derek Lovley
Acetate Oxidation Coupled To Fe(Iii) Reduction In Hyperthermophilic Microorganisms, Jason M. Tor, Kazem Kashefi, Derek Lovley
Derek Lovley
No hyperthermophilic microorganisms have previously been shown to anaerobically oxidize acetate, the key extracellular intermediate in the anaerobic oxidation of organic matter. Here we report that two hyperthermophiles, Ferroglobus placidus and “Geoglobus ahangari,” grow at 85°C by oxidizing acetate to carbon dioxide, with Fe(III) serving as the electron acceptor. These results demonstrate that acetate could potentially be metabolized within the hot microbial ecosystems in which hyperthermophiles predominate, rather than diffusing to cooler environments prior to degradation as has been previously proposed.
Direct And Fe(Ii) Mediated Reduction Of Technetium By Fe(Iii)-Reducing Bacteria, Jon R. Lloyd, V. A. Sole, Catherine V. Van Praagh, Derek Lovley
Direct And Fe(Ii) Mediated Reduction Of Technetium By Fe(Iii)-Reducing Bacteria, Jon R. Lloyd, V. A. Sole, Catherine V. Van Praagh, Derek Lovley
Derek Lovley
The dissimilatory Fe(III)-reducing bacterium Geobacter sulfurreducens reduced and precipitated Tc(VII) by two mechanisms. Washed cell suspensions coupled the oxidation of hydrogen to enzymatic reduction of Tc(VII) to Tc(IV), leading to the precipitation of TcO(2) at the periphery of the cell. An indirect, Fe(II)-mediated mechanism was also identified. Acetate, although not utilized efficiently as an electron donor for direct cell-mediated reduction of technetium, supported the reduction of Fe(III), and the Fe(II) formed was able to transfer electrons abiotically to Tc(VII). Tc(VII) reduction was comparatively inefficient via this indirect mechanism when soluble Fe(III) citrate was supplied to the cultures but was enhanced …
Lack Of Production Of Electron-Shuttling Compounds Or Solubilization Of Fe(Iii) During Reduction Of Insoluble Fe(Iii) Oxide Of Geobacter Metallireducens, Kelly P. Nevin, Derek Lovley
Lack Of Production Of Electron-Shuttling Compounds Or Solubilization Of Fe(Iii) During Reduction Of Insoluble Fe(Iii) Oxide Of Geobacter Metallireducens, Kelly P. Nevin, Derek Lovley
Derek Lovley
Studies with the dissimilatory Fe(III)-reducing microorganismGeobacter metallireducens demonstrated that the common technique of separating Fe(III)-reducing microorganisms and Fe(III) oxides with semipermeable membranes in order to determine whether the Fe(III) reducers release electron-shuttling compounds and/or Fe(III) chelators is invalid. This raised doubts about the mechanisms for Fe(III) oxide reduction by this organism. However, several experimental approaches indicated that G. metallireducens does not release electron-shuttling compounds and does not significantly solubilize Fe(III) during Fe(III) oxide reduction. These results suggest that G. metallireducens directly reduces insoluble Fe(III) oxide.