Nanoscale Environments Associated with Bioweathering of a Mg-Fe-Pyroxene

Microorganisms are believed to create microenvironments leading to reaction products not predictable from equilibrium thermodynamics and to unique biomineral morphologies. Unambiguous evidence for such environments is, however, rare in natural samples. We have used scanning transmission x-ray micros...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2005-01, Vol.102 (4), p.979-982
Main Authors: Benzerara, Karim, Yoon, Tae Hyun, Menguy, Nicolas, Tyliszczak, Tolek, Brown, Gordon E., Ernst, W. G.
Format: Article
Language:English
Subjects:
Calcite
Crystals
Dissolution
Iron compounds
Magnesium
Microorganisms
Mineralogy
Molecules
Oxidation
Physical Sciences
Polysaccharides
Precipitation
Pyroxenes
Silicates
Transmission electron microscopy
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Summary:Microorganisms are believed to create microenvironments leading to reaction products not predictable from equilibrium thermodynamics and to unique biomineral morphologies. Unambiguous evidence for such environments is, however, rare in natural samples. We have used scanning transmission x-ray microscopy and spectromicroscopy at the sub-40-nm scale, coupled with transmission electron microscopy, to examine bioweathering products on a meteoritic Fe-Mg-orthopyroxene colonized by a filamentous microorganism. Our measurements reveal an amorphous Al-rich layer beneath the microorganism, calcium carbonates of unique morphology intimately associated with polysaccharides adjacent to the microorganism, and regions surrounding the microorganism with different iron oxidation states. Our results confirm the presence of different microenvironments at this microorganism-mineral interface and provide unique nanometer-scale views of microbially controlled pyroxene weathering products.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0409029102