Paradoxo: bactéria 'antiga' com genes que codificam proteína 'moderna'

Molecular Biology and Evolution 19:1637-1639 (2002)
© 2002 Society for Molecular Biology and Evolution

The Paradox of the "Ancient" Bacterium Which Contains "Modern" Protein-Coding Genes

Heather Maughan*, C. William Birky Jr.*, Wayne L. Nicholson*, William D. Rosenzweig and Russell H. Vreeland

*Graduate Interdisciplinary Program in Genetics,
Department of Ecology and Evolutionary Biology,
Department of Veterinary Science and Microbiology, University of Arizona; and
Department of Biology, West Chester University

The isolation of microorganisms from ancient materials and the verification that they are as old as the materials from which they were isolated continue to be areas of controversy. Almost without exception, bacteria isolated from ancient material have proven to closely resemble modern bacteria at both morphological and molecular levels. This fact has historically been used by critics to argue that these isolates are not ancient but are modern contaminants introduced either naturally after formation of the surrounding material (for further details, see Hazen and Roeder 2001 and the reply by Powers, Vreeland, and Rosenzweig 2001) or because of flaws in the methodology of sample isolation (reviewed recently in Vreeland and Rosenzweig 2002 ).

Such criticism has been addressed experimentally by the development of highly rigorous protocols for sample selection, surface sterilization, and contamination detection and control procedures. Using the most scrupulous and well-documented sampling procedures and contamination-protection techniques reported to date, Vreeland, Rosenzweig, and Powers (2000) reported the isolation of a sporeforming bacterium, Bacillus strain 2-9-3, from a brine inclusion within a halite crystal recovered from the 250-Myr-old Permian Salado Formation in Carlsbad, NM.

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