Thermophiles as Candidate Iron-Reducing Bacteria For the Putative Biogenetic Magnetite in Banded Iron Formations
Abstract
The temperature of the Archaean-Palaeoproterozoic ocean was likely consistent with physiological requirements of thermophilic species being present. In this study, we compared the crystallochemistry and lattice constants of magnetite crystals produced by Thermoanaerobacter sp. TOR39, Geobacter and Shewanella and the slightly altered magnetite from BIF of Hamersley, Western Australia. The lattice constants of TOR39-magnetite and the BIF-magnetite were similar, being 8.3901 and 8.3869 Å respectively. The lattice constant of magnetite produced by Geobacter is more close to perfect stoichiometry (8.4038 Å), however, the magnetite produced by Shewanella experienced oxidization has a much smaller value (8.3522 Å). The stoichiometries of TOR39-magnetite was Fe3+[Fe3+1.1217Fe2+0.8175--0.0608]O4 and that of BIF-magnetite was quite similar being Fe3+[Fe3+0.9963Fe2+1.0056]O4. The stoichiometry, lattice constant and crystal size collectively indicated that TOR39-magnetite was similar to BIF-magnetite. The Mössbauer spectroscopy indicated the existence of a Fe(III)-salt, possibly Fe3+OH(CH3COO)2 in the magnetite lamina of BIF which was widely detected in the magnetite-assemblages of iron-reducing bacterial cultures that contained acetate. This is evidence that supports a potential role for thermophiles such as Thermoanaerobacter in the biogenesis of magnetite in BIF. The magnetite crystals produced by cultures of Shewanella, Geobacter, magnetotactic bacteria and those synthesized from green rust appeared less similar to BIF-magnetite by either their crystallochemistry or their optimized growth temperatures.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.B21B0345L
- Keywords:
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- 0419 Biomineralization;
- 0444 Evolutionary geobiology;
- 0448 Geomicrobiology;
- 0473 Paleoclimatology and paleoceanography (3344;
- 4900)