Alkane biodegradation and dynamics of phylogenetic subgroups of sulfate-reducing bacteria in an anoxic coastal marine sediment artificially contaminated with oil Gilles Miralles a , Vincent Grossi a,1 , Monique Acquaviva a , Robert Duran b , Jean Claude Bertrand a , Philippe Cuny a, * a Laboratoire de Microbiologie, de Ge ´ochimie et d’Ecologie Marines, CNRS-UMR 6117, Centre d’Oce ´anologie de Marseille, Campus de Luminy, Case 901, 13288 Marseille Cedex 9, France b Laboratoire d’Ecologie Mole ´culaire, IBEAS, EA 3525, Universite ´ de Pau et des Pays de l’Adour, Avenue de l’Universite ´, BP1155, 64013 Pau Cedex, France Received 26 September 2006; received in revised form 16 January 2007; accepted 17 January 2007 Available online 6 March 2007 Abstract For 503 days, unoiled control and artificially oiled sediments were incubated in situ at 20 m water depth in a Mediterranean coastal area. Degradation of the aliphatic fraction of the oil added was followed by GC–MS. At the same time, terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA encoding genes was used to detect dynamics in the sulfate-reducing bacteria (SRB) com- munity in response to the oil contamination. Specific polymerase chain reaction (PCR) primer sets for five generic or suprageneric groups of SRB were used for PCR amplification of DNA extracted from sediments. During the experiment, hydrocarbons from C 17 to C 30 were significantly degraded even in strictly anoxic sediment layers. Of the five SRB groups, only two groups were detected in the sediments (control and oiled), namely the Desulfococcus–Desulfonema–Desulfosarcina-like group and the Desulfovibrio–Desulfomicrobium-like group. Statistical analysis of community patterns revealed dynamic changes over time within these two groups following the contami- nation. Significant differences in community patterns were recorded in artificially oiled compared with control sediments. Cloning and sequencing of 16S rRNA encoding genes performed after 503 days showed that many of the most abundant sequences were closely related to hydrocarbonoclastic SRB which could have played an active role in the observed biodegradation of aliphatic hydrocarbons. Results from the present study provide useful information on the dynamics of dominant SRB in heavily oil-contaminated sediments and their potential for anaerobic biodegradation for the treatment of spilled oil in anoxic marine environments. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Sulfate-reducing bacteria; In situ hydrocarbon biodegradation; T-RFLP fingerprinting; Field experiment; Mediterranean Sea 1. INTRODUCTION Marine sediments, particularly those in coastal areas, are commonly polluted with petroleum hydrocarbons (PHC) as a consequence of the extensive use of petroleum compounds by mankind. With the exception of the most superficial layer, the bulk of organic matter-rich marine sediments con- taminated by PHC are assumed to be anoxic (Canfield et al., 1993). The fact that oxygen is not available in all environ- ments where hydrocarbons occur has repeatedly raised the question as to whether or not the biodegradation of hydro- carbons is possible under anoxic conditions, and if so to what extent. It was not until the late 1980s that novel types of microorganisms were definitively shown to degrade hydrocarbons under strictly anoxic conditions. Since then, evidence has been accumulating to suggest that there is 0045-6535/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2007.01.033 * Corresponding author. Tel.: +33 491 829 147; fax: +33 491 829 641. E-mail address: philippe.cuny@univmed.fr (P. Cuny). 1 Present address: Pale ´oenvironnements et Pale ´obiosphe `re, CNRS- UMR 5125 PEPS, Universite ´ Claude Bernard Lyon 1, Campus scientifi- que de la Doua, Ba ˆtiment Ge ´ode, 69622 Villeurbanne Cedex, France. www.elsevier.com/locate/chemosphere Chemosphere 68 (2007) 1327–1334