SREL Reprint #2323

Bacterial mineralization patterns in basaltic aquifers: implications for possible life in martian meteorite ALH84001

Kathie L. Thomas-Keprta1, David S. McKay2, Susan J. Wentworth1, Todd O. Stevens3, Anne E. Taunton4,
Carlton C. Allen1, Annette Coleman5, Everett K. Gibson, Jr.6, and Christopher S. Romanek7

1Lockheed Martin Space Mission Systems and Services, 2400 NASA Road 1, Houston, Texas 77058
2NASA Johnson Space Center, S, Houston, Texas 77058
3Battelle, Pacific Northwest Laboratory, PO. Box 999, Richland, Washington 99352
4University of Wisconsin, Department of Geology, Weeks Hall. 1215 Dayton Street, Madison, Wisconsin 53706
5Biomedical Department, Brown University, Providence, Rhode Island 02912
6NASA Johnson Space Center, SN2, Houston. Texas 77058
7Savannah River Ecology Laboratory, Drawer E, University of Georgia, Aiken, South Carolina 29802

Abstract: To explore the formation and preservation of biogenic features in igneous rocks, we have examined the organisms in experimental basaltic microcosms using scanning and transmission electron microscopy. Four types of microorganisms were recognized on the basis of size, morphology, and chemical composition. Some of the organisms mineralized rapidly, whereas others show no evidence of mineralization. Many mineralized cells are hollow and do not contain evidence of, microstructure. Filaments, either attached or no longer attached to organisms, are common. Unattached filaments are mineralized and are most likely bacterial appendages (e.g., prosthecae). Features similar in size and morphology to unattached, mineralized filaments are recognized in martian meteorite ALH84001.

SREL Reprint #2323

Thomas-Keprta, K.L., D.S. McKay, S.J. Wentworth, T.O. Stevens, A.E. Taunton, C.C. Allen, A. Coleman, E.K. Gibson, Jr., and C.S. Romanek. 1998. Bacterial mineralization patterns in basaltic aquifers: implications for possible life in martian meteorite ALH84001. Geology 26:1031-1034.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).