[meteorite-list] Nanobacteria-Like Calcite Single Crystals At The Surface of Tataouine Meteorite

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:22:34 2004
Message-ID: <200306051641.JAA01520_at_zagami.jpl.nasa.gov>

http://www.pnas.org/cgi/content/abstract/0832464100v1

Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0832464100

Geology
Nanobacteria-like calcite single crystals at the
surface of the Tataouine meteorite

Karim Benzerara *, Nicolas Menguy *, François Guyot *, Christian Dominici ,
and Philippe Gillet

*Laboratoire de Minéralogie-Cristallographie, Unité Mixte de Recherche 7590
Centre National de la Recherche Scientifique and Institut de Physique du Globe
de Paris, 4 Place Jussieu, 75252 Paris
Cedex, France; Laboratoire CP2M Faculté des Sciences et Techniques de
Saint Jerôme, Université d'Aix-Marseille, III,
F-13397 Marseille Cedex 20, France; and Laboratoire des Sciences de la Terre,
Ecole Normale Supérieure Lyon, 46 Allée d'Italie, 69007 Lyon Cedex, France

Communicated by Russell J. Hemley, Carnegie Institution, Washington, DC,
April 24, 2003 (received for review March 8, 2003)

Nanobacteria-like objects evidenced at the surface of the orthopyroxenes of the
Tataouine meteorite in South Tunisia have been studied by scanning and
transmission electron microscopies. A method of micromanipulation has been
developed to ensure that exactly the same objects were studied by both methods.
We have shown that the nanobacteria-like objects are spatially correlated with
filaments of microorganisms that colonized the surface of the meteoritic
pyroxene during its 70 years of residence in the aridic Tataouine soil.
Depressions of a few micrometers in depth are observed in the pyroxene
below the carbonates, indicating preferential dissolution of the pyroxene and
calcite precipitation at these locations. The nanobacteria-like small rods
that constitute calcium carbonate rosettes are well crystallized calcite
single crystals surrounded by a thin amorphous layer of carbonate composition
that smoothes the crystal edges and induces rounded shapes. Those morphologies
are unusual for calcite single crystals observed in natural samples. A survey
of recent literature suggests that the intervention of organic compounds
derived from biological activity is likely in their formation.

 To whom correspondence should be addressed.

E-mail: benzerar_at_lmcp.jussieu.fr.
Received on Thu 05 Jun 2003 12:41:18 PM PDT