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Boeuf D, Eppley JM, Mende DR, Malmstrom RR, Woyke T, DeLong EF. Metapangenomics reveals depth-dependent shifts in metabolic potential for the ubiquitous marine bacterial SAR324 lineage. Microbiome 2021; 9:172. [PMID: 34389059 PMCID: PMC8364033 DOI: 10.1186/s40168-021-01119-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/22/2021] [Indexed: 06/01/2023]
Abstract
BACKGROUND Oceanic microbiomes play a pivotal role in the global carbon cycle and are central to the transformation and recycling of carbon and energy in the ocean's interior. SAR324 is a ubiquitous but poorly understood uncultivated clade of Deltaproteobacteria that inhabits the entire water column, from ocean surface waters to its deep interior. Although some progress has been made in elucidating potential metabolic traits of SAR324 in the dark ocean, very little is known about the ecology and the metabolic capabilities of this group in the euphotic and twilight zones. To investigate the comparative genomics, ecology, and physiological potential of the SAR324 clade, we examined the distribution and variability of key genomic features and metabolic pathways in this group from surface waters to the abyss in the North Pacific Subtropical Gyre, one of the largest biomes on Earth. RESULTS We leveraged a pangenomic ecological approach, combining spatio-temporally resolved single-amplified genome, metagenomic, and metatranscriptomic datasets. The data revealed substantial genomic diversity throughout the SAR324 clade, with distinct depth and temporal distributions that clearly differentiated ecotypes. Phylogenomic subclade delineation, environmental distributions, genomic feature similarities, and metabolic capacities revealed strong congruence. The four SAR324 ecotypes delineated in this study revealed striking divergence from one another with respect to their habitat-specific metabolic potentials. The ecotypes living in the dark or twilight oceans shared genomic features and metabolic capabilities consistent with a sulfur-based chemolithoautotrophic lifestyle. In contrast, those inhabiting the sunlit ocean displayed higher plasticity energy-related metabolic pathways, supporting a presumptive photoheterotrophic lifestyle. In epipelagic SAR324 ecotypes, we observed the presence of two types of proton-pumping rhodopsins, as well as genomic, transcriptomic, and ecological evidence for active photoheterotrophy, based on xanthorhodopsin-like light-harvesting proteins. CONCLUSIONS Combining pangenomic and both metagenomic and metatranscriptomic profiling revealed a striking divergence in the vertical distribution, genomic composition, metabolic potential, and predicted lifestyle strategies of geographically co-located members of the SAR324 bacterial clade. The results highlight the utility of metapangenomic approaches employed across environmental gradients, to decipher the properties and variation in function and ecological traits of specific phylogenetic clades within complex microbiomes. Video abstract.
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Affiliation(s)
- Dominique Boeuf
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Manoa, Honolulu, HI 96822 USA
| | - John M. Eppley
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Manoa, Honolulu, HI 96822 USA
| | - Daniel R. Mende
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Manoa, Honolulu, HI 96822 USA
| | | | - Tanja Woyke
- DOE Joint Genome Institute, Berkeley, CA 94720 USA
| | - Edward F. DeLong
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Manoa, Honolulu, HI 96822 USA
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Pereira O, Hochart C, Boeuf D, Auguet JC, Debroas D, Galand PE. Seasonality of archaeal proteorhodopsin and associated Marine Group IIb ecotypes (Ca. Poseidoniales) in the North Western Mediterranean Sea. ISME J 2021; 15:1302-1316. [PMID: 33288859 PMCID: PMC8115670 DOI: 10.1038/s41396-020-00851-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 11/09/2020] [Accepted: 11/18/2020] [Indexed: 01/04/2023]
Abstract
The Archaea Marine Group II (MGII) is widespread in the world's ocean where it plays an important role in the carbon cycle. Despite recent discoveries on the group's metabolisms, the ecology of this newly proposed order (Candidatus Poseidoniales) remains poorly understood. Here we used a combination of time-series metagenome-assembled genomes (MAGs) and high-frequency 16S rRNA data from the NW Mediterranean Sea to test if the taxonomic diversity within the MGIIb family (Candidatus Thalassarchaeaceae) reflects the presence of different ecotypes. The MAGs' seasonality revealed a MGIIb family composed of different subclades that have distinct lifestyles and physiologies. The vitamin metabolisms were notably different between ecotypes with, in some, a possible link to sunlight's energy. Diverse archaeal proteorhodopsin variants, with unusual signature in key amino acid residues, had distinct seasonal patterns corresponding to changing day length. In addition, we show that in summer, archaea, as opposed to bacteria, disappeared completely from surface waters. Our results shed light on the diversity and the distribution of the euryarchaeotal proteorhodopsin, and highlight that MGIIb is a diverse ecological group. The work shows that time-series based studies of the taxonomy, seasonality, and metabolisms of marine prokaryotes is critical to uncover their diverse role in the ocean.
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Affiliation(s)
- Olivier Pereira
- Sorbonne Universités, CNRS, Laboratoire d'Ecogéochimie des Environnements Benthiques (LECOB), Observatoire Océanologique, Banyuls sur Mer, France
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Southern University of Science and Technology, Shenzhen, China
| | - Corentin Hochart
- Sorbonne Universités, CNRS, Laboratoire d'Ecogéochimie des Environnements Benthiques (LECOB), Observatoire Océanologique, Banyuls sur Mer, France
| | - Dominique Boeuf
- Daniel K. Inouye Center for Microbial Oceanography, Research and Education, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, United States, Honolulu, HI, 96822, USA
| | - Jean Christophe Auguet
- MARBEC, Université de Montpellier, CNRS, Ifremer, IRD, Montpellier, France, Montpellier, France
| | - Didier Debroas
- Université Clermont Auvergne, CNRS, Laboratoire Microorganismes: Genome et Environnement, 63000, Clermont-Ferrand, France
| | - Pierre E Galand
- Sorbonne Universités, CNRS, Laboratoire d'Ecogéochimie des Environnements Benthiques (LECOB), Observatoire Océanologique, Banyuls sur Mer, France.
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Mende DR, Boeuf D, DeLong EF. Persistent Core Populations Shape the Microbiome Throughout the Water Column in the North Pacific Subtropical Gyre. Front Microbiol 2019; 10:2273. [PMID: 31632377 PMCID: PMC6779783 DOI: 10.3389/fmicb.2019.02273] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 09/18/2019] [Indexed: 01/23/2023] Open
Abstract
Marine microbial communities are responsible for many important ecosystem processes in the oceans. Their variability across time and depths is well recognized, but mostly at a coarse-grained taxonomic resolution. To gain a deeper perspective on ecological patterns of bacterioplankton diversity in the North Pacific Subtropical Gyre, we characterized bacterioplankton communities throughout the water column at a fine-grained taxonomic level with a focus on temporally persistent (core) populations. Considerable intra-clade microdiversity was evident in virtually every microbial clade examined. While some of the most abundant populations comprised only a small fraction of the intra-clade microdiversity, they formed a temporally persistent core within a more diverse array of less abundant ephemeral populations. The depth-stratified population structure within many phylogenetically disparate clades suggested that ecotypic variation was the rule among most planktonic bacterial and archaeal lineages. Our results suggested that the abundant, persistent core populations comprised the bulk of the biomass within any given clade. As such, we postulate that these core populations are largely responsible for microbially driven ecosystem processes, and so represent ideal targets for elucidating key microbial processes in the open-ocean water column.
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Affiliation(s)
- Daniel R Mende
- Daniel K. Inouye Center for Microbial Oceanography, Research and Education, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, United States
| | - Dominique Boeuf
- Daniel K. Inouye Center for Microbial Oceanography, Research and Education, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, United States
| | - Edward F DeLong
- Daniel K. Inouye Center for Microbial Oceanography, Research and Education, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, United States
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Olson DK, Yoshizawa S, Boeuf D, Iwasaki W, DeLong EF. Proteorhodopsin variability and distribution in the North Pacific Subtropical Gyre. ISME J 2018; 12:1047-1060. [PMID: 29476140 PMCID: PMC5864233 DOI: 10.1038/s41396-018-0074-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 11/21/2017] [Accepted: 12/05/2017] [Indexed: 11/17/2022]
Abstract
Proteorhodopsin is a light-activated retinal-containing proton pump found in many marine bacteria. These photoproteins are globally distributed in the ocean’s photic zone and are capable of generating a proton motive force across the cell membrane. We investigated the phylogenetic diversity, distribution, and abundance of proteorhodopsin encoding genes in free-living bacterioplankton in the North Pacific Subtropical Gyre, leveraging a gene catalog derived from metagenomic samples from the ocean’s surface to 1000 m depth. Proteorhodopsin genes were identified at all depths sampled, but were most abundant at depths shallower than 200 m. The majority of proteorhodopsin gene sequences (60.9%) belonged to members of the SAR11 lineage, with remaining sequences distributed among other diverse taxa. We observed variations in the conserved residues involved in ion pumping and spectral tuning, and biochemically confirmed four different proton pumping proteorhodopsin motifs, including one unique to deep-water SAR11. We also identified a new group of putative proteorhodopsins having unknown function. Our results reveal a broad organismal and unexpected depth distribution for different proteorhodopsin types, as well as substantial within-taxon variability. These data provide a framework for exploring the ecological relevance of proteorhodopsins and their spatiotemporal variation and function in heterotrophic bacteria in the open ocean.
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Affiliation(s)
- Daniel K Olson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawaii, Honolulu, HI, 96822, USA
| | - Susumu Yoshizawa
- Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, 277-8564, Japan
| | - Dominique Boeuf
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawaii, Honolulu, HI, 96822, USA
| | - Wataru Iwasaki
- Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, 277-8564, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0032, Japan
| | - Edward F DeLong
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawaii, Honolulu, HI, 96822, USA.
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Hubas C, Boeuf D, Jesus B, Thiney N, Bozec Y, Jeanthon C. A Nanoscale Study of Carbon and Nitrogen Fluxes in Mats of Purple Sulfur Bacteria: Implications for Carbon Cycling at the Surface of Coastal Sediments. Front Microbiol 2017; 8:1995. [PMID: 29114241 PMCID: PMC5660696 DOI: 10.3389/fmicb.2017.01995] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/28/2017] [Indexed: 11/25/2022] Open
Abstract
Mass blooms of purple sulfur bacteria growing seasonally on green stranded macroalgae have a major impact on the microbial composition and functionality of intertidal mats. To explore the active anoxygenic phototrophic community in purple bacterial mats from the Roscoff Aber Bay (Brittany, France), we conducted a combined approach including molecular and high-resolution secondary ion mass spectrometry (NanoSIMS) analyses. To investigate the dynamics of carbon and nitrogen assimilation activities, NanoSIMS was coupled with a stable isotope probing (SIP) experiment and a compound specific isotope analysis (CSIA) of fatty acid methyl ester (FAME). Sediment samples were incubated with 13C- and/or 15N-labeled acetate, pyruvate, bicarbonate and ammonium. NanoSIMS analysis of 13C - and 15N -incubated samples showed elevated incorporations of 13C - and 15N in the light and of 13C -acetate in the dark into dense populations of spherical cells that unambiguously dominated the mats. These results confirmed CSIA data that ranked vaccenic acid, an unambiguous marker of purple sulfur bacteria, as the most strongly enriched in the light after 13C -acetate amendment and indicated that acetate uptake, the most active in the mat, was not light-dependent. Analysis of DNA- and cDNA-derived pufM gene sequences revealed that Thiohalocapsa-related clones dominated both libraries and were the most photosynthetically active members of the mat samples. This study provides novel insights into the contribution of purple sulfur bacteria to the carbon cycle during their seasonal developments at the sediment surface in the intertidal zone.
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Affiliation(s)
- Cédric Hubas
- Muséum National d'Histoire Naturelle, UMR BOREA, MNHN-CNRS-UCN-UPMC-IRD-UA, Station de Biologie Marine de Concarneau, Concarneau, France
| | - Dominique Boeuf
- CNRS, Station Biologique de Roscoff, Adaptation et Diversité en Milieu Marin, Roscoff, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR 7144, Station Biologique de Roscoff, Adaptation et Diversité en Milieu Marin, Roscoff, France
| | - Bruno Jesus
- EA2160, Laboratoire Mer Molécules Santé, Université de Nantes, Nantes, France.,BioISI - Biosystems & Integrative Sciences Institute, Campo Grande University of Lisbon, Faculty of Sciences, Lisbon, Portugal
| | - Najet Thiney
- Muséum National d'Histoire Naturelle, UMR BOREA, MNHN-CNRS-UCN-UPMC-IRD-UA, Bâtiment Arthropodes, Paris, France
| | - Yann Bozec
- CNRS, Station Biologique de Roscoff, Adaptation et Diversité en Milieu Marin, Roscoff, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR 7144, Station Biologique de Roscoff, Adaptation et Diversité en Milieu Marin, Roscoff, France
| | - Christian Jeanthon
- CNRS, Station Biologique de Roscoff, Adaptation et Diversité en Milieu Marin, Roscoff, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR 7144, Station Biologique de Roscoff, Adaptation et Diversité en Milieu Marin, Roscoff, France
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Boeuf D, Lami R, Cunnington E, Jeanthon C. Summer Abundance and Distribution of Proteorhodopsin Genes in the Western Arctic Ocean. Front Microbiol 2016; 7:1584. [PMID: 27790192 PMCID: PMC5061748 DOI: 10.3389/fmicb.2016.01584] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/21/2016] [Indexed: 11/13/2022] Open
Abstract
Proteorhodopsins (PR) are phylogenetically diverse and highly expressed proton pumps in marine bacterial communities. The phylogenetic diversity and in situ expression of the main PR groups in polar off-shore, coastal and estuarine waters is poorly known and their abundance has not yet been reported. Here, we show that PR gene sequences of the southern Beaufort Sea including MacKenzie shelf and estuary are mainly affiliated to Gammaproteobacteria, Alphaproteobacteria, and Bacteroidetes. Substantial overlap (78%) between DNA- and cDNA-based librairies indicated in situ PR transcription within a large fraction of PR-containing community. Sets of specific qPCR primers were designed to measure the absolute abundances of the major PR types. Spatial and depth profiles showed that PR-containing bacteria were abundant throughout the photic zone, comprising up to 45% of total bacteria. Although their abundance varied greatly with location and depth, Alphaproteobacteria predominated in the PR community in all water masses, with SAR11 as the major PR type. Low nutrient concentrations rather than light were the environmental drivers that best explained the abundance and distribution of arctic PR types. Together, our data suggests that PR-based phototrophy could be the major phototrophic prokaryotic process during the Arctic Ocean summer.
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Affiliation(s)
- Dominique Boeuf
- CNRS, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France; Sorbonne Universités - UPMC Université Paris 06, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France
| | - Raphaël Lami
- CNRS, USR 3579, Laboratoire de Biodiversité et Biotechnologies MicrobiennesBanyuls-sur-Mer, France; Sorbonne Universités - UPMC Université Paris 06, USR 3579, Observatoire OcéanologiqueBanyuls-sur-Mer, France
| | - Emelyne Cunnington
- CNRS, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France; Sorbonne Universités - UPMC Université Paris 06, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France
| | - Christian Jeanthon
- CNRS, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France; Sorbonne Universités - UPMC Université Paris 06, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France
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Boeuf D, Audic S, Brillet-Guéguen L, Caron C, Jeanthon C. MicRhoDE: a curated database for the analysis of microbial rhodopsin diversity and evolution. Database (Oxford) 2015; 2015:bav080. [PMID: 26286928 PMCID: PMC4539915 DOI: 10.1093/database/bav080] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 07/25/2015] [Indexed: 11/12/2022]
Abstract
Microbial rhodopsins are a diverse group of photoactive transmembrane proteins found in all three domains of life and in viruses. Today, microbial rhodopsin research is a flourishing research field in which new understandings of rhodopsin diversity, function and evolution are contributing to broader microbiological and molecular knowledge. Here, we describe MicRhoDE, a comprehensive, high-quality and freely accessible database that facilitates analysis of the diversity and evolution of microbial rhodopsins. Rhodopsin sequences isolated from a vast array of marine and terrestrial environments were manually collected and curated. To each rhodopsin sequence are associated related metadata, including predicted spectral tuning of the protein, putative activity and function, taxonomy for sequences that can be linked to a 16S rRNA gene, sampling date and location, and supporting literature. The database currently covers 7857 aligned sequences from more than 450 environmental samples or organisms. Based on a robust phylogenetic analysis, we introduce an operational classification system with multiple phylogenetic levels ranging from superclusters to species-level operational taxonomic units. An integrated pipeline for online sequence alignment and phylogenetic tree construction is also provided. With a user-friendly interface and integrated online bioinformatics tools, this unique resource should be highly valuable for upcoming studies of the biogeography, diversity, distribution and evolution of microbial rhodopsins. Database URL: http://micrhode.sb-roscoff.fr.
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Affiliation(s)
- Dominique Boeuf
- CNRS, UMR 7144, Marine Phototrophic Prokaryotes Team, Sorbonne Universités, UPMC Univ Paris 06, UMR 7144, Oceanic Plankton Group
| | - Stéphane Audic
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7144, Oceanic Plankton Group, CNRS, UMR 7144, Team Evolution des Protistes et Ecosystèmes Pélagiques and
| | | | - Christophe Caron
- CNRS, UPMC, FR2424, ABiMS, Station Biologique de Roscoff, F-29680 Roscoff, France
| | - Christian Jeanthon
- CNRS, UMR 7144, Marine Phototrophic Prokaryotes Team, Sorbonne Universités, UPMC Univ Paris 06, UMR 7144, Oceanic Plankton Group,
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Boeuf D, Cottrell MT, Kirchman DL, Lebaron P, Jeanthon C. Summer community structure of aerobic anoxygenic phototrophic bacteria in the western Arctic Ocean. FEMS Microbiol Ecol 2013; 85:417-32. [PMID: 23560623 DOI: 10.1111/1574-6941.12130] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 04/02/2013] [Accepted: 04/02/2013] [Indexed: 11/26/2022] Open
Abstract
Aerobic anoxygenic phototrophic (AAP) bacteria are found in a range of aquatic and terrestrial environments, potentially playing unique roles in biogeochemical cycles. Although known to occur in the Arctic Ocean, their ecology and the factors that govern their community structure and distribution in this extreme environment are poorly understood. Here, we examined summer AAP abundance and diversity in the North East Pacific and the Arctic Ocean with emphasis on the southern Beaufort Sea. AAP bacteria comprised up to 10 and 14% of the prokaryotic community in the bottom nepheloid layer and surface waters of the Mackenzie plume, respectively. However, relative AAP abundances were low in offshore waters. Environmental pufM clone libraries revealed that AAP bacteria in the Alphaproteobacteria and Betaproteobacteria classes dominated in offshore and in river-influenced surface waters, respectively. The most frequent AAP group was a new uncultivated betaproteobacterial clade whose abundance decreased along the salinity gradient of the Mackenzie plume even though its photosynthetic genes were actively expressed in offshore waters. Our data indicate that AAP bacterial assemblages represented a mixture of freshwater and marine taxa mostly restricted to the Arctic Ocean and highlight the substantial influence of riverine inputs on their distribution in coastal environments.
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Affiliation(s)
- Dominique Boeuf
- UPMC, Univ Paris VI, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique, Roscoff, France
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Michotey V, Guasco S, Boeuf D, Morezzi N, Durieux B, Charpy L, Bonin P. Spatio-temporal diversity of free-living and particle-attached prokaryotes in the tropical lagoon of Ahe atoll (Tuamotu Archipelago) and its surrounding oceanic waters. Mar Pollut Bull 2012; 65:525-537. [PMID: 22289391 DOI: 10.1016/j.marpolbul.2012.01.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 01/04/2012] [Accepted: 01/06/2012] [Indexed: 05/31/2023]
Abstract
Spatio-temporal variability of prokaryotic water column communities inside and outside a Polynesian tropical lagoon subjected to pearl oysters farming was assessed in terms of abundance by quantitative PCR and diversity by DGGE. Communities and operational taxonomic units (OTUs) were analysed according to dry/rainy seasons and free-living/particle-attached state. Bacterial density was higher in the lagoon compared to ocean and a seasonal trend was observed. No influence of the localisation within lagoon or of the planktonic/attached states was noticed on bacterial abundance and diversity. The OTUs belonged to Cyanobacteria, to heterotrophic groups in Proteobacteria and Flavobacteria. Archaeal abundance showed seasonal tendency and particle-prevalence, but no effect of lagoon or oceanic location was observed. Lagoon and oceanic archaeal diversity were different and Euryarchaeota (MG-II, MBG, and Halobacteria) were detected. During the dry season, planktonic and particle-associated community differed, whereas at rainy season, both communities were similar and included members usually associated with coral.
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Affiliation(s)
- V Michotey
- Aix-Marseille Université, Mediterranean Institute of Oceanography (MIO), 13288 Marseille Cedex 09, France.
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