LETTER
Crystal morphology of MV-1 magnetite
SIMON J. CLEMETT,1 KATHIE L. THOMAS-KEPRTA,1* JOEL
SHlMMIN,2 MARY MORPHEW,2 J. RICHARD McINTOSH,2
DENNIS A. BAZYLINSKI,3 JOSEPH L. KIRSCHVINK,4 SUSAN
J. WENTWORTH,1 DAVID S. MCKAY,5 HOJATOLLAH V ALI,6
EVERETT K. GIBSON JR.,5 AND CHRISTOPHER S. ROMANEK1
1Lockheed Martin Space Operations (NASNJohnson Space Center
Astrobilogy Institute), 2400 NASA Road 1, Mail Code C23, Houston, Texas
77058, U.S,A.
2Department of Molecular, Cellular & Developmental Biology,
University of Colorado, Boulder, Colorado 80309,U.S.A.
3Iowa State University, Department of Microbiology, 207 Science
I, Ames, Iowa 50011, U.S.A.
4Califomia Institute of Technology, Division of Geological
and Planetary Sciences, 1200 East California Boulevard, Pasadena, California
91125, U.S.A.
5NASA, Johnson Space Center, Houston, Texas 77058, U.S.A.
6McGill University, Department of Earth and Planetary Sciences,
3450 University Street, Montreal, PQ H3A 2A7, Canada
7Savannah River Ecology Laboratory, Drawer E, University of
Georgia, Aiken, South Carolina 29802, U.S.A.
ABSTRACT
Intracellular magnetite (Fe304) crystals produced
by magnetotactic bacteria strain MV-1 are in the single-domain size range,
and are chemically pure. We have previously suggested that they exhibit
an unusual crystal habit described as truncated hexa-octahedral. Such
a crystal morphology has not been demonstrated for any inorganic population
of magnetite, nor would it be expected, given considerations of symmetry
and free energy. By inference, this morphology is a physical signature
of a biological origin. Here we report data from transmission electron
microscope (TEM) tomography of such crystals isolated from magnetotactic
bacteria, which confirm the unusual geometry, originally proposed from
classical TEM tilt imaging.
SREL Reprint #2743
Clemett, S. J., K. L. Thomas-Keprta, J. Shimmin, M. Morphew, J. R. McIntosh, D. A. Bazylinski, J. L. Kirschvink, S. J. Wentworth, D. S. McKay, H. Vali, E. K. Gibson, Jr. and C. S. Romanek. 2002. Crystal morphology of MV-1 magnetite. American Mineralogist 87:1727-1730.
