Microbial diversity on the Tatahouine meteorite

available online at http://meteoritics.org 1249 © The Meteoritical Society, 2006. Printed in USA. Microbial diversity on the Tatahouine meteorite Karim BENZERARA1*, Virginie CHAPON2, David MOREIRA3, Purificación LÓPEZ-GARCÍA3, François GUYOT1, and Thierry HEULIN2 1Laboratoire de Minéralogie-Cristallographie, UMR 7590 and Institut de Physique du Globe de Paris, 4 place Jussieu, 75252 Paris Cedex, France 2CEA/Cadarache, DSV-DEVM, Laboratoire d’Ecologie Microbienne de la Rhizosphère, UMR 6191 CNRS-CEA-Université de la Méditerranée, F-13108 Saint-Paul-lez-Durance, France 3Unité d’Ecologie, Systématique et Evolution, UMR CNRS 8079, Université Paris-Sud, 91405 Orsay Cedex, France *Corresponding author. E-mail: [email protected] (Received 07 February 2006; revision accepted 25 April 2006) Abstract–Biological processes can alter the chemistry and mineralogy of meteorites in a very short time, even in cold or hot deserts. It is thus important to assess the diversity of microorganisms that colonize meteorites in order to better understand their physiological capabilities. Microscopy observations of Tatahouine meteorite fragments that were exposed for 70 years in the Sahara desert showed that they were colonized by morphologically diverse biomorphs. A molecular diversity study based on 16S rRNA gene amplification of DNA supported the conclusion that a huge taxonomic diversity of prokaryotes colonized the Tatahouine meteorite in less than 70 years in the Tatahouine sand. Eleven different bacterial divisions were evidenced, among which Cytophaga-FlexibacterBacteroides (CFB), Cyanobacteria, and Alpha-Proteobacteria were dominantly represented. Crenarcheota were also detected. Most of the Tatahouine meteorite phylotypes were related to sequences identified in the surrounding Tatahouine more generally to sequences detected in soils. Some of them, in particular many of the archaeal phylotypes, were detected in arid regions in association with desert varnish. The results suggest that the diversity of the clone library generated from the meteorite fraction was reduced compared with that of the Tatahouine sand clone library, which can be explained as the result of partial colonization of the meteorite and/or a specific selection of colonizing bacteria by the substrate. We discuss the possibility that several groups detected in this study may play a prominent role in the various alteration processes detected at the surface of the Tatahouine meteorite.Biological processes can alter the chemistry and mineralogy of meteorites in a very short time, even in cold or hot deserts. It is thus important to assess the diversity of microorganisms that colonize meteorites in order to better understand their physiological capabilities. Microscopy observations of Tatahouine meteorite fragments that were exposed for 70 years in the Sahara desert showed that they were colonized by morphologically diverse biomorphs. A molecular diversity study based on 16S rRNA gene amplification of DNA supported the conclusion that a huge taxonomic diversity of prokaryotes colonized the Tatahouine meteorite in less than 70 years in the Tatahouine sand. Eleven different bacterial divisions were evidenced, among which Cytophaga-FlexibacterBacteroides (CFB), Cyanobacteria, and Alpha-Proteobacteria were dominantly represented. Crenarcheota were also detected. Most of the Tatahouine meteorite phylotypes were related to sequences identified in the surrounding Tatahouine more generally to sequences detected in soils. Some of them, in particular many of the archaeal phylotypes, were detected in arid regions in association with desert varnish. The results suggest that the diversity of the clone library generated from the meteorite fraction was reduced compared with that of the Tatahouine sand clone library, which can be explained as the result of partial colonization of the meteorite and/or a specific selection of colonizing bacteria by the substrate. We discuss the possibility that several groups detected in this study may play a prominent role in the various alteration processes detected at the surface of the Tatahouine meteorite.