title: Distribution of Sulfate-Reducing Communities from Estuarine to Marine Bay Waters.
abstract: Estuaries are highly dynamic ecosystems in which freshwater and seawater mix together. Depending on tide and river inflows, particles originating from rivers or from the remobilization of sediments accumulate in the water column. Due to the salinity gradient and the high heterotrophic activity in the estuarine plume, hypoxic and anoxic microniches may form in oxygenated waters, sustaining favorable conditions for resuspended anaerobic microorganisms. In this context, we tested the hypothesis that anaerobic sulfate-reducing prokaryotes may occur in the water column of the Adour River. Using 16S ribosomal RNA (rRNA) and dsrAB-based terminal restriction fragment length polymorphism (T-RFLP) techniques, we characterized total prokaryotic and sulfate-reducing communities along a gradient from estuarine to marine bay waters. Sulfate-reducing prokaryotes were further characterized by the description of dsrB genes and the cultivation of sulfidogenic anaerobic microorganisms. As a result, physical-chemical parameters had a significant effect on water bacterial diversity and community structure along the studied gradient. The concentration of cultured sulfidogenic microorganisms ranged from 1 to 60 × 103cells l-1in the water column. Sulfate-reducing prokaryotes occurring in estuarine waters were closely related to microorganisms previously detected in freshwater sediments, suggesting an estuarine origin, mainly by the remobilization of the sediments. In the marine bay station, sediment-derived sulfate-reducing prokaryotes were not cultured anymore, probably due to freshwater dilution, increasing salinity and extended oxic stress. Nevertheless, isolates related to the type strain Desulfovibrio oceani were cultured from the diluted plume and deep marine waters, indicating the occurrence of autochthonous sulfate-reducing bacteria offshore.
authors: Equipe Environnement et Microbiologie, IPREM UMR CNRS 5254, Université de Pau et des Pays de l'Adour, IBEAS, BP 1155, 64013, Pau Cedex, France. colin.yannick@gmail.com.|INRA, UMR 1136 INRA/Université de Lorraine, Interactions Arbres Micro-organismes, Centre de Nancy, 54280, Champenoux, France. colin.yannick@gmail.com.
authors: Yannick
authors: Y
authors: Colin
authors: Equipe Environnement et Microbiologie, IPREM UMR CNRS 5254, Université de Pau et des Pays de l'Adour, IBEAS, BP 1155, 64013, Pau Cedex, France.
authors: Marisol
authors: M
authors: Goñi-Urriza
authors: Equipe Environnement et Microbiologie, IPREM UMR CNRS 5254, Université de Pau et des Pays de l'Adour, IBEAS, BP 1155, 64013, Pau Cedex, France.
authors: Claire
authors: C
authors: Gassie
authors: Equipe Environnement et Microbiologie, IPREM UMR CNRS 5254, Université de Pau et des Pays de l'Adour, IBEAS, BP 1155, 64013, Pau Cedex, France.
authors: Elisabeth
authors: E
authors: Carlier
authors: Laboratoire de Chimie Analytique Bio-Inorganique et Environnement (LCABIE), IPREM UMR CNRS 5254, Université de Pau et des Pays de l'Adour, Pau, France.
authors: Mathilde
authors: M
authors: Monperrus
authors: Equipe Environnement et Microbiologie, IPREM UMR CNRS 5254, Université de Pau et des Pays de l'Adour, IBEAS, BP 1155, 64013, Pau Cedex, France.
authors: Rémy
authors: R
authors: Guyoneaud
mesh_terms: D061006:Bays / Q000382:microbiology*; D044822:Biodiversity; D003901:Desulfovibrio / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D017753:Ecosystem; D063366:Estuaries; D005618:Fresh Water / Q000382:microbiology; D019015:Geologic Sediments / Q000382:microbiology*; D010084:Oxidation-Reduction; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D054712:Salinity; D012623:Seawater / Q000382:microbiology*; D013431:Sulfates / Q000378:metabolism*
chemical_list: D012336:RNA, Ribosomal, 16S; D013431:Sulfates
keywords: Estuarine plume; Marine bay waters; Sediments remobilization; Sulfate-reducing bacteria