Thermophilic anaerobic microorganisms with the ability to reduce sulfur compounds (e.g., sulfate and/or thiosulfate) were isolated from water samples collected from about 2000 meters depth at in situ temperatures of 70°C in a geothermal well from the Paris Basin (France). Chemical and isotopic analyses show that microbial sulfate reduction occurred in the samples. Two strains were characterized by both DNA/DNA hybridization and 16S rRNA gene sequence analysis, which indicated that they are most closely related to Thermotoga elfii, a thiosulfate-reducing bacterium, and Archaeoglobus fulgidus, a sulfate- and thiosulfate-reducing archaeon. Besides thiosulfate reduction using H2 as energy source, both isolates are shown to be able to retrieve energy from H2/Fe(III), a metabolic capability of importance in a deep biosphere context. It is suggested that T. elfii and A. fulgidus could be used, either as pure culture or as a consortium, in future laboratory studies aiming at better understanding microbial iron (III) and sulfate/thiosulfate reduction, hydrogen production/consumption, as well as the effect of microorganisms on the evolution of CO2 in deep aquifers. The present work examines numerous culture conditions and demonstrates that in spite of similarities in phylogenetic/genetic characteristics and in growth conditions, there are significant phenotypic differences between the isolated archaeal strain and the type strain of A. fulgidus. These differences, evidenced by a proteomic study, should be taken into account and could be useful parameters to be studied in the deep aquifers by geomicrobiological laboratories.
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Document Type: Research Article
Laboratoire de Microbiologie IRD, IFR-BAIM, Universites de Provence et de la Mediterranee, Marseille, CEDEX 09, France
Institut de Biologie Structurale et de Microbiologie, Unite de Bioenergetique et Ingenierie des Proteines (BIP), CNRS, Marseille, CEDEX 20, France
BRGM, Environment and Process Division, Orleans, CEDEX 2, France
Laboratoire de Mineralogie, IMPMC and IPGP, CNRS, Universites de Paris 6, Paris, France
Publication date: 2009-03-01
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