title: Dynamics of bacterial assemblages and removal of polycyclic aromatic hydrocarbons in oil-contaminated coastal marine sediments subjected to contrasted oxygen regimes.
abstract: To study the impact of oxygen regimes on the removal of polycylic aromatic hydrocarbons (PAHs) in oil-spill-affected coastal marine sediments, we used a thin-layer incubation method to ensure that the incubated sediment was fully oxic, anoxic, or was influenced by oxic-anoxic switches without sediment stirring. Hydrocarbon content and microbial assemblages were followed during 60 days to determine PAH degradation kinetics and microbial community dynamics according to the oxygenation regimes. The highest PAH removal, with 69 % reduction, was obtained at the end of the experiment under oxic conditions, whereas weaker removals were obtained under oscillating and anoxic conditions (18 and 12 %, respectively). Bacterial community structure during the experiment was determined using a dual 16S rRNA genes/16S rRNA transcripts approach, allowing the characterization of metabolically active bacteria responsible for the functioning of the bacterial community in the contaminated sediment. The shift of the metabolically active bacterial communities showed that the selection of first responders belonged to Pseudomonas spp. and Labrenzia sp. and included an unidentified Deltaproteobacteria-irrespective of the oxygen regime-followed by the selection of late responders adapted to the oxygen regime. A novel unaffiliated phylotype (B38) was highly active during the last stage of the experiment, at which time, the low-molecular-weight (LMW) PAH biodegradation rates were significant for permanent oxic- and oxygen-oscillating conditions, suggesting that this novel phylotype plays an active role during the restoration phase of the studied ecosystem.
authors.affiliation: Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288, Marseille, France. cecile.militon@univ-amu.fr.|Campus de Luminy, case 901, 163 avenue de Luminy, 13288, Marseille Cedex 09, France. cecile.militon@univ-amu.fr.
authors.forename: Cécile
authors.initials: C
authors.lastname: Militon
authors.affiliation: Centre de Documentation, de Recherche et d'Expérimentations sur les pollutions accidentelles des Eaux, 715 rue Alain Colas, CS 41836, 29218, Brest, France.
authors.forename: Ronan
authors.initials: R
authors.lastname: Jézéquel
authors.affiliation: Université de Toulouse; INP, UPS; EcoLab (Laboratoire écologie fonctionnelle et environnement), 118 Route de Narbonne, 31062, Toulouse, France.|CNRS; EcoLab, 31062, Toulouse, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Gilbert
authors.affiliation: Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288, Marseille, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Corsellis
authors.affiliation: Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288, Marseille, France.
authors.forename: Léa
authors.initials: L
authors.lastname: Sylvi
authors.affiliation: Equipe Environnement et Microbiologie, MELODY group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau Cedex, France.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Cravo-Laureau
authors.affiliation: Equipe Environnement et Microbiologie, MELODY group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau Cedex, France.
authors.forename: Robert
authors.initials: R
authors.lastname: Duran
authors.affiliation: Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288, Marseille, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Cuny
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001673:Biodegradation, Environmental; D017753:Ecosystem; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D006838:Hydrocarbons / Q000032:analysis / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D059392:Petroleum Pollution; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D006838:Hydrocarbons; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D010100:Oxygen
keywords: Aerobic and anaerobic hydrocarbon degradation; Bacterial communities; DGGE; Dual 16S rRNA/rRNA gene; Marine sediment; Oxic/anoxic oscillation; PAHs