Ecology and evolution of bacterial microdiversity

Authors

  • Michael Schloter,

    Corresponding author
    1. GSF-National Research Center for Environment and Health, Institute of Soil Ecology, Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
      *Corresponding author. Tel.: +49 (89) 31872304; Fax: +49 (89) 31873376, E-mail address: schloter@gsf.de
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  • Michael Lebuhn,

    1. GSF-National Research Center for Environment and Health, Institute of Soil Ecology, Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
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  • Thierry Heulin,

    1. DSV-DEVM, Laboratoire d'Écologie Microbienne de la Rhizosphere, UMR163 CNRS-CEA, CEA-Cadarache, F-13108 St. Paul lez Durance, France
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  • Anton Hartmann

    1. GSF-National Research Center for Environment and Health, Institute of Soil Ecology, Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
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*Corresponding author. Tel.: +49 (89) 31872304; Fax: +49 (89) 31873376, E-mail address: schloter@gsf.de

Abstract

Using high resolution molecular fingerprinting techniques like random amplification of polymorphic DNA, repetitive extragenic palindromic PCR and multilocus enzyme electrophoresis, a high bacterial diversity below the species and subspecies level (microdiversity) is revealed. It became apparent that bacteria of a certain species living in close association with different plants either as associated rhizosphere bacteria or as plant pathogens or symbiotic organisms, typically reflect this relationship in their genetic relatedness. The strain composition within a population of soil bacterial species at a given field site, which can be identified by these high resolution fingerprinting techniques, was markedly influenced by soil management and soil features. The observed bacterial microdiversity reflected the conditions of the habitat, which select for better adapted forms. In addition, influences of spatial separation on specific groupings of bacteria were found, which argue for the occurrence of isolated microevolution. In this review, examples are presented of bacterial microdiversity as influenced by different ecological factors, with the main emphasis on bacteria from the natural environment. In addition, information available from some of the first complete genome sequences of bacteria (Helicobacter pylori and Escherichia coli) was used to highlight possible mechanisms of molecular evolution through which mutations are created; these include mutator enzymes. Definitions of bacterial species and subspecies ranks are discussed in the light of detailed information from whole genome typing approaches.

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