@article {615,
	title = {The periplasmic 9.6-kilodalton c-type cytochrome of Geobacter sulfurreducens is not an electron shuttle to Fe(III).},
	journal = {J Bacteriol},
	volume = {181},
	year = {1999},
	month = {1999 Dec},
	pages = {7647-9},
	abstract = {Geobacter sulfurreducens contains a 9.6-kDa c-type cytochrome that was previously proposed to serve as an extracellular electron shuttle to insoluble Fe(III) oxides. However, when the cytochrome was added to washed-cell suspensions of G. sulfurreducens it did not enhance Fe(III) oxide reduction, whereas similar concentrations of the known electron shuttle, anthraquinone-2,6-disulfonate, greatly stimulated Fe(III) oxide reduction. Furthermore, analysis of the extracellular c-type cytochromes in cultures of G. sulfurreducens demonstrated that the dominant c-type cytochrome was not the 9.6-kDa cytochrome, but rather a 41-kDa cytochrome. These results and other considerations suggest that the 9.6-kDa cytochrome is not an important extracellular electron shuttle to Fe(III) oxides.},
	keywords = {Cytochrome c Group, Electron Transport, Electrophoresis, Polyacrylamide Gel, Ferric Compounds, Gram-Negative Anaerobic Bacteria, Molecular Weight, Periplasm},
	issn = {0021-9193},
	author = {Lloyd, J R and Blunt-Harris, E L and Lovley, D R}
}
@article {617,
	title = {Role of humic-bound iron as an electron transfer agent in dissimilatory Fe(III) reduction.},
	journal = {Appl Environ Microbiol},
	volume = {65},
	year = {1999},
	month = {1999 Sep},
	pages = {4252-4},
	abstract = {The dissimilatory Fe(III) reducer Geobacter metallireducens reduced Fe(III) bound in humic substances, but the concentrations of Fe(III) in a wide range of highly purified humic substances were too low to account for a significant portion of the electron-accepting capacities of the humic substances. Furthermore, once reduced, the iron in humic substances could not transfer electrons to Fe(III) oxide. These results suggest that other electron-accepting moieties in humic substances, such as quinones, are the important electron-accepting and shuttling agents under Fe(III)-reducing conditions.},
	keywords = {Deltaproteobacteria, Electron Transport, Ferric Compounds, Humic Substances, Iron, Oxidation-Reduction},
	issn = {0099-2240},
	author = {Lovley, D R and Blunt-Harris, E L}
}
@article {620,
	title = {Microbiological evidence for Fe(III) reduction on early Earth.},
	journal = {Nature},
	volume = {395},
	year = {1998},
	month = {1998 Sep 3},
	pages = {65-7},
	abstract = {It is generally considered that sulphur reduction was one of the earliest forms of microbial respiration, because the known microorganisms that are most closely related to the last common ancestor of modern life are primarily anaerobic, sulphur-reducing hyperthermophiles. However, geochemical evidence indicates that Fe(III) is more likely than sulphur to have been the first external electron acceptor of global significance in microbial metabolism. Here we show that Archaea and Bacteria that are most closely related to the last common ancestor can reduce Fe(III) to Fe(II) and conserve energy to support growth from this respiration. Surprisingly, even Thermotoga maritima, previously considered to have only a fermentative metabolism, could grow as a respiratory organism when Fe(III) was provided as an electron acceptor. These results provide microbiological evidence that Fe(III) reduction could have been an important process on early Earth and suggest that microorganisms might contribute to Fe(III) reduction in modern hot biospheres. Furthermore, our discovery that hyperthermophiles that had previously been thought to require sulphur for cultivation can instead be grown without the production of toxic and corrosive sulphide, should aid biochemical investigations of these poorly understood organisms.},
	keywords = {Earth (Planet), Electron Transport, Environmental Microbiology, Ferric Compounds, Gram-Negative Anaerobic Bacteria, Oxidation-Reduction, Thermoproteaceae},
	issn = {0028-0836},
	doi = {10.1038/25720},
	author = {Vargas, M and Kashefi, K and Blunt-Harris, E L and Lovley, D R}
}
