ENVIRONMENTAL MICROBIOLOGY Identification of Sulfur-Cycle Prokaryotes in a Low-Sulfate Lake (Lake Pavin) Using aprA and 16S rRNA Gene Markers Corinne Biderre-Petit & Delphine Boucher & Jan Kuever & Patrick Alberic & Didier Jézéquel & Brigitte Chebance & Guillaume Borrel & Gérard Fonty & Pierre Peyret Received: 3 May 2010 / Accepted: 27 October 2010 / Published online: 25 November 2010 # Springer Science+Business Media, LLC 2010 Abstract Geochemical researches at Lake Pavin, a low- sulfate-containing freshwater lake, suggest that the dominant biogeochemical processes are iron and sulfate reduction, and methanogenesis. Although the sulfur cycle is one of the main active element cycles in this lake, little is known about the sulfate-reducer and sulfur-oxidizing bacteria. The aim of this study was to assess the vertical distribution of these microbes and their diversities and to test the hypothesis suggesting that only few SRP populations are involved in dissimilatory sulfate reduc- tion and that Epsilonproteobacteria are the likely key players in the oxidative phase of sulfur cycle by using a PCR aprA gene-based approach in comparison with a 16S rRNA gene-based analysis. The results support this hypothesis. Finally, this preliminary work points strongly the likelihood of novel metabolic processes upon the availability of sulfate and other electron acceptors. Introduction Microorganisms catalyze a wide variety of reactions, mainly in energy generation for growth, which ensures their involvement in all element cycles important for life. Electronic supplementary material The online version of this article (doi:10.1007/s00248-010-9769-4) contains supplementary material, which is available to authorized users. C. Biderre-Petit : B. Chebance : G. Borrel : G. Fonty Laboratoire Microorganismes: Génome et Environnement, Clermont Université, Université Blaise Pascal, BP 10448, F63000, Clermont-Ferrand, France C. Biderre-Petit : D. Boucher : B. Chebance : G. Borrel : G. Fonty : P. Peyret UMR CNRS 6023, Université Blaise Pascal, 63000, Clermont-Ferrand, France D. Boucher : P. Peyret Laboratoire Microorganismes: Génome et Environnement, Clermont Université, Université d’Auvergne, BP 10448, F63000, Clermont-Ferrand, France J. Kuever Bremen Institute for Materials Testing, Paul-Feller-Strasse 1, 28199, Bremen, Germany P. Alberic Institut des Sciences de la Terre d’Orléans (ISTO), Bâtiment Géosciences, BP 6759, F 45067, Orléans cedex 2, France P. Alberic UMR CNRS 6113, Bâtiment Géosciences, BP 6759, F 45067, Orléans cedex 2, France D. Jézéquel Laboratoire de Géochimie des Eaux, Institut de Physique du Globe de Paris, Université Paris 7, 35 rue Hélène Brion, 75205, Paris Cedex 13, France D. Jézéquel UMR CNRS 7154, Université Paris 7, 75205, Paris Cedex 13, France P. Peyret (*) Laboratoire Microorganismes: Génome et Environnement, UMR CNRS 6023, Université Blaise Pascal, 63177, Aubière, France e-mail: pipeyret@univ-bpclermont.fr Microb Ecol (2011) 61:313–327 DOI 10.1007/s00248-010-9769-4