Diversity and distribution of subterranean bacteria in groundwater at Oklo in Gabon, Africa, as determined by 16S rRNA gene sequencing

Authors

  • K. PEDERSEN,

    Corresponding author
    1. Department of General and Marine Microbiology, The Lundberg Institute, Göteborg University, Medicinaregatan 9C, S-413 90 Göteborg, Sweden
      Tel.: + 46-31-7732578. Fax: + 46-31-7732599. E-mail: pedersen@gmm.gu.se
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  • J. ARLINGER,

    1. Department of General and Marine Microbiology, The Lundberg Institute, Göteborg University, Medicinaregatan 9C, S-413 90 Göteborg, Sweden
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  • L. HALLBECK,

    1. Department of General and Marine Microbiology, The Lundberg Institute, Göteborg University, Medicinaregatan 9C, S-413 90 Göteborg, Sweden
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  • C. PETTERSSON

    1. *Department of Water and Environmental Studies, Linköping University, S-581 83 Linköping, Sweden
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  • This paper is a result of our interest in the deep subterranean biosphere, that has been studied at University of Göteborg under the direction of Karsten Pedersen since 1987. Much of this work relates to performance assessment of radioactive waste disposal. Johanna Arlinger is responsible for the technical performance of our DNA work and is now also an experienced African traveller. Lotta Hallbeck has produced a series of papers on Gallionella ferruginea and is responsible for the sequence analysis on GCG and with PHYLIP. Catharina Pettersson holds a position at Linköping University where she studies the relationship between organic molecules such as fulvic acids and metals in natural environments.

Tel.: + 46-31-7732578. Fax: + 46-31-7732599. E-mail: pedersen@gmm.gu.se

Abstract

This paper describes how groundwater was sampled, DNA extracted, amplified and cloned and how information available in the ribosomal 16S rRNA gene was used for mapping diversity and distribution of subterranean bacteria in groundwater at the Bangombé site in the Oklo region. The results showed that this site was inhabited by a diversified population of bacteria. Each borehole was dominated by species that did not dominate in any of the other boreholes; a result that probably reflects documented differences in the geochemical environment. Two of the sequences obtained were identified at genus level to represent Acinetobacter and Zoogloea, but most of the 44 sequences found were only distantly related to species in the DNA database. The deepest borehole, BAX01 (105 m), had the highest number of bacteria and also total organic carbon (TOC). This borehole harboured only Proteobacteria beta group sequences while sequences related to Proteobacteria beta, gamma and delta groups and Gram-positive bacteria were found in the other four boreholes. Two of the boreholes, BAX02 (34 m) and BAX04 (10 m) had many 16S rRNA gene sequences in common and they also had similar counts of bacteria, content of TOC, pH and equal conductivity, suggesting a hydraulic connection between them.

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