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Pringault, O., Viret, H., & Duran, R. (2010). Influence of microorganisms on the removal of nickel in tropical marine sediments (New Caledonia). Marine Pollution Bulletin, 61(7–12), 530–541.
Résumé: The removal of nickel in marine tropical sediments (New Caledonia) was studied in microcosms. Removal of Ni2+ was strongly enhanced by the presence of bacteria, with rates up to twofold higher than those observed under sterilized conditions. After 8 days of incubation, Ni2+ concentration in the water column ranged from 30% to 50% of the initial concentration according to sediment origin. Addition of glucose stimulated bacterial processes and resulted in a complete disappearance of Ni2+ in the water phase. Incubation under anoxic conditions slightly affects the microbial structure inferred from T-RFLP analysis irrespective of Ni2+ spiking, whereas incubation under oxic conditions resulted to moderate modification of the microbial structure, changes that might be more marked in the presence of Ni2+. Five different T-RFs were observed in almost all microcosms with relative abundance between 5% and 30%. Incubation with glucose resulted in the dominance of a common T-RF, with relative abundance up to 39%.
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Pringault, O., Viret, H., & Duran, R. (2012). Interactions between Zn and bacteria in marine tropical coastal sediments. Environ. Sci. Pollut. Res., 19(3), 879–892.
Résumé: Purpose The main goals of this study were (1) to examine the effects of zinc on the microbial community structure of anthropogenically impacted sediments in a tropical coastal ecosystem and (2) to determine whether these microbial benthic communities may enhance the adsorption of zinc. Methods The interactions between zinc and bacteria in tropical sediments were studied in sediment microcosms amended with 2.5 mg L-1 of Zn in the water phase and incubated for 8 days under different environmental conditions, oxic/anoxic and glucose addition. At the end of incubation, microbial structure was assessed by molecular fingerprints (T-RFLP) analysis and Zn speciation in the sediment was determined by sequential extraction. Results In the three studied sediments, Zn spiking resulted in only slight changes in bacterial community structure. In contrast, the addition of low concentrations of glucose (5mM) strongly modified the bacterial community structure: <20% of similarity with the initial structure concomitant with a strong diminution of the specific richness. Overall, these results suggest that highly labile organic matter has a larger impact on microbial structure than heavy metal. These weak impacts of Zn on bacteria diversity might be partly explained by (1) the strong adsorption of Zn in the presence of bacteria and/or (2) the incorporation of Zn into a nonbioavailable fraction. Nevertheless, Zn spiking resulted in significant changes in nutrient cycles, suggesting that bacterial metabolisms were impacted by the heavy metal. This led to an increase in nutrient supplies to the water column, potentially enhancing eutrophication in a nutrient-limited, oligotrophic ecosystem.
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