The desert of Tataouine: an extreme environment that hosts a wide diversity of microorganisms and radiotolerant bacteria

Authors

  • Angélique Chanal,

    1. LEMIR, DEVM, DSV, UMR 6191 CNRS-CEA-Université Aix-Marseille II, IFR 112, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France.
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    • Both authors contributed equally to this work.

  • Virginie Chapon,

    Corresponding author
    1. LEMIR, DEVM, DSV, UMR 6191 CNRS-CEA-Université Aix-Marseille II, IFR 112, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France.
      *E-mail virginie.chapon@cea.fr; Tel. (+33) 4 42 256 371; Fax (+33) 4 42 256 648.
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    • Both authors contributed equally to this work.

  • Karim Benzerara,

    1. LEMIR, DEVM, DSV, UMR 6191 CNRS-CEA-Université Aix-Marseille II, IFR 112, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France.
    2. LMCP, UMR 7590 and Institut de Physique du Globe de Paris, 4 place Jussieu, F-75252 Paris, France.
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  • Mohamed Barakat,

    1. LEMIR, DEVM, DSV, UMR 6191 CNRS-CEA-Université Aix-Marseille II, IFR 112, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France.
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  • Richard Christen,

    1. UMR 6543, CNRS – Université de Nice Sophia Antipolis, Centre de Biochimie, Parc Valrose, F-06108 Nice, France.
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  • Wafa Achouak,

    1. LEMIR, DEVM, DSV, UMR 6191 CNRS-CEA-Université Aix-Marseille II, IFR 112, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France.
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  • Frédéric Barras,

    1. LCB, CNRS, 31, chemin J. Aiguier, F-13402 Marseille, France.
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  • Thierry Heulin

    1. LEMIR, DEVM, DSV, UMR 6191 CNRS-CEA-Université Aix-Marseille II, IFR 112, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France.
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*E-mail virginie.chapon@cea.fr; Tel. (+33) 4 42 256 371; Fax (+33) 4 42 256 648.

Summary

The phylogenetic diversity of prokaryotic communities exposed to arid conditions in the hot desert of Tataouine (south Tunisia) was estimated with a combination of a culture and – molecular-based analysis. Thirty-one isolates, representative of each dominant morphotypes, were affiliated to Actinobacteria, Firmicutes, Proteobacteria and the CFB group while none related to Archaea. Analysis of 16S rRNA gene libraries revealed the presence of species related to Bacteria and Archaea. Sequences related to Archaea were all affiliated to the non-thermophilic Crenarchaeota subgroup. Bacterial sequences were dominated by Proteobacteria, Actinobacteria and Acidobacteria; a few sequences were distributed among eight others phyla, including Thermus/Deinococcus relatives. A correlation between tolerance to desiccation and to radiation has been demonstrated for the radiotolerant bacteria Deinococcus radiodurans. Because bacteria living in the hot desert of Tataouine are one way or another tolerant to desiccation, we investigate whether they could also be tolerant to radiation. Exposition of soil samples to intense gamma radiation yields Bacillus, Thermus/Deinococcus and α-Proteobacteria relatives. Four of these strains correspond to radiotolerant species as revealed by evaluation of the resistance levels of the individual cultures. A detailed analysis of the resistance levels for two Thermus/Deinococcus and two α-Proteobacteria relatives revealed that they correspond to new radiotolerant species.

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