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Auteur Goni-Urriza, M.; Moussard, H.; Lafabrie, H.; Carré, C.; Bouvy, M.; Sakka Hlaili, A.; Pringault, O.
Titre Consequences of contamination on the interactions between phytoplankton and bacterioplankton Type Article scientifique
Année 2018 Publication Revue Abrégée Chemosphere
Volume 195 Numéro Pages 212-222
Mots-Clés bizerte lagoon; bacterial communities; polycyclic aromatic-hydrocarbons; surface sediments; functional diversity; ecosystem; sediment resuspension; coastal lagoon; nutrient enrichment; tropical lagoon
Résumé Sediment resuspension can provoke strong water enrichment in nutrients, contaminants, and microorganisms. Microcosm incubations were performed in triplicate for 96 h, with lagoon and offshore waters incubated either with sediment elutriate or with an artificial mixture of contaminants issued from sediment resuspension. Sediment elutriate provoked a strong increase in microbial biomass, with little effects on the phytoplankton and bacterioplankton community structures. Among the pool of contaminants released, few were clearly identified as structuring factors of phytoplanktdn and bacterioplankton communities, namely simazine, Cu, Sn, Ni, and Cr. Effects were more pronounced in the offshore waters, suggesting a relative tolerance of the lagoon microbial communities to contamination. The impacts of contamination on the microbial community structure were direct or indirect, depending on the nature and the strength of the interactions between phytoplankton and bacterioplankton. (C) 2017 Elsevier Ltd. All rights reserved.
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ISSN 0045-6535 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2265
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Auteur Gounand, I.; Daufresne, T.; Gravel, D.; Bouvier, C.; Bouvier, T.; Combe, M.; Gougat-Barbera, C.; Poly, F.; Torres-Barcelo, C.; Mouquet, N.
Titre Size evolution in microorganisms masks trade-offs predicted by the growth rate hypothesis Type Article scientifique
Année 2016 Publication Revue Abrégée Proc. R. Soc. B-Biol. Sci.
Volume 283 Numéro 1845 Pages 20162272
Mots-Clés Bacteria; bacterial community; biological stoichiometry; cell-size; escherichia-coli; experimental evolution; fresh-water; growth rate hypothesis; inorganic polyphosphate; intrinsic growth; mechanistic approach; Pseudomonas fluorescens; resource competition; r/K strategies; Stoichiometry; variable environment
Résumé Adaptation to local resource availability depends on responses in growth rate and nutrient acquisition. The growth rate hypothesis (GRH) suggests that growing fast should impair competitive abilities for phosphorus and nitrogen due to high demand for biosynthesis. However, in microorganisms, size influences both growth and uptake rates, which may mask trade-offs and instead generate a positive relationship between these traits (size hypothesis, SH). Here, we evolved a gradient of maximum growth rate (mu(max)) from a single bacterium ancestor to test the relationship among mu(max), competitive ability for nutrients and cell size, while controlling for evolutionary history. We found a strong positive correlation between mu(max) and competitive ability for phosphorus, associated with a trade-off between mu(max) and cell size: strains selected for high mu(max) were smaller and better competitors for phosphorus. Our results strongly support the SH, while the trade-offs expected under GRH were not apparent. Beyond plasticity, unicellular populations can respond rapidly to selection pressure through joint evolution of their size and maximum growth rate. Our study stresses that physiological links between these traits tightly shape the evolution of competitive strategies.
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Volume de collection Numéro de collection Edition
ISSN 0962-8452 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2055
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Auteur Gros, O.; Elisabeth, N.H.; Gustave, S.D.D.; Caro, A.; Dubilier, N.
Titre Plasticity of symbiont acquisition throughout the life cycle of the shallow-water tropical lucinid Codakia orbiculata (Mollusca: Bivalvia) Type Article scientifique
Année 2012 Publication Revue Abrégée Environ. Microbiol.
Volume 14 Numéro 6 Pages 1584-1595
Mots-Clés bacteria; bathymodiolus-azoricus; cold; endosymbiont transmission; gill-endosymbionts; identification; in-situ hybridization; population; seeps; sulfur; vertical transmission
Résumé In marine invertebrates that acquire their symbionts from the environment, these are generally only taken up during early developmental stages. In the symbiosis between lucinid clams and their intracellular sulfur-oxidizing bacteria, it has been shown that the juveniles acquire their symbionts from an environmental stock of free-living symbiont forms, but it is not known if adult clams are still competent to take up symbiotic bacteria from the environment. In this study, we investigated symbiont acquisition in adult specimens of the lucinid clam Codakia orbiculata, using transmission electron microscopy, fluorescence in situ hybridization, immunohistochemistry and PCR. We show here that adults that had no detectable symbionts after starvation in aquaria for 6 months, rapidly reacquired symbionts within days after being returned to their natural environments in the field. Control specimens that were starved and then exposed to seawater aquaria with sulfide did not reacquire symbionts. This indicates that the reacquisition of symbionts in the starved clams returned to the field was not caused by high division rates of a small pool of remaining symbionts that we were not able to detect with the methods used here. Immunohistochemistry with an antibody against actin, a protein involved in the phagocytosis of intracellular bacteria, showed that actin was expressed at the apical ends of the gill cells that took up symbionts, providing further evidence that the symbionts were acquired from the environment. Interestingly, actin expression was also observed in symbiont-containing cells of untreated lucinids freshly collected from the environment, indicating that symbiont acquisition from the environment occurs continuously in these clams throughout their lifetime.
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ISSN 1462-2912 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 784
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Auteur Hugoni, M.; Escalas, A.; Bernard, C.; Nicolas, S.; Jézéquel, D.; Vazzoler, F.; Sarazin, G.; Leboulanger, C.; Bouvy, M.; Got, P.; Ader, M.; Troussellier, M.; Agogué, H.
Titre Spatiotemporal variations in microbial diversity across the three domains of life in a tropical thalassohaline lake (Dziani Dzaha, Mayotte Island) Type Article scientifique
Année 2018 Publication Revue Abrégée Molecular Ecology
Volume 27 Numéro 23 Pages 4775-4786
Mots-Clés archaea; bacteria; eukaryotes; extreme environment; metabarcoding; thalassohaline lake
Résumé Thalassohaline ecosystems are hypersaline environments originating from seawater in which sodium chloride is the most abundant salt and the pH is alkaline. Studies focusing on microbial diversity in thalassohaline lakes are still scarce compared with those on athalassohaline lakes such as soda lakes that have no marine origin. In this work, we investigated multiple facets of bacterial, archaeal and eukaryotic diversity in the thalassohaline Lake Dziani Dzaha using a metabarcoding approach. We showed that bacterial and archaeal diversity were mainly affected by contrasting physicochemical conditions retrieved at different depths. While photosynthetic microorganisms were dominant in surface layers, chemotrophic phyla (Firmicutes or Bacteroidetes) and archaeal methanogens dominated deeper layers. In contrast, eukaryotic diversity was constant regardless of depth and was affected by seasonality. A detailed focus on eukaryotic communities showed that this constant diversity profile was the consequence of the high predominance of Picocystis salinarum, while nondominant eukaryotic groups displayed seasonal diversity turnover. Altogether, our results provided an extensive description of the diversity of the three domains of life in an unexplored extreme environment and showed clear differences in the responses of prokaryotic and eukaryotic communities to environmental conditions.
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Volume de collection Numéro de collection Edition
ISSN 1365-294x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2460
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Auteur Jacquemot, L.; Bettarel, Y.; Monjol, J.; Corre, E.; Halary, S.; Desnues, C.; Bouvier, T.; Ferrier-Pages, C.; Baudoux, A.-C.
Titre Therapeutic potential of a new jumbo phage that infects Vibrio coralliilyticus, a widespread coral pathogen Type Article scientifique
Année 2018 Publication Revue Abrégée Front. Microbiol.
Volume 9 Numéro Pages 2501
Mots-Clés bacterial pathogen; bacteriophages; coral disease; database; disease; phage therapy; phage-host interactions; phi-kz; ralstonia-solanacearum; reef ecosystems; sequence; transfer-rna genes; Vibrio coralliilyticus; viral genomics; virulence factors
Résumé Biological control using bacteriophages is a promising approach for mitigating the devastating effects of coral diseases. Several phages that infect Vibrio coralliilyticus, a widespread coral pathogen, have been isolated, suggesting that this bacterium is permissive to viral infection and is, therefore, a suitable candidate for treatment by phage therapy. In this study, we combined functional and genomic approaches to evaluate the therapeutic potential of BONAISHI, a novel V. coralliilyticus phage, which was isolated from the coral reef in Van Phong Bay (Vietnam). BONAISHI appears to be strictly lytic for several pathogenic strains of V. coralliilyticus and remains infectious over a broad range of environmental conditions. This candidate has an unusually large dsDNA genome (303 kb), with no genes that encode known toxins or implicated in lysogeny control. We identified several proteins involved in host lysis, which may offer an interesting alternative to the use of whole bacteriophages for controlling V. coralliilyticus. A preliminary therapy test showed that adding BONAISHI to an infected culture of Symbiodinium sp. cells reduced the impact of V. coralliilyticus on Symbiodinium sp. photosynthetic activity. This study showed that BONAISHI is able to mitigate V. coralliilyticus infections, making it a good candidate for phage therapy for coral disease.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1664-302x ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2446
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