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  • 1
    Online Resource
    Online Resource
    Spatiotemporal variations in microbial diversity across the three domains of life in a tropical thalassohaline lake (Dziani Dzaha, Mayotte Island)
    Wiley ; 2018
    In:  Molecular Ecology Vol. 27, No. 23 ( 2018-12), p. 4775-4786
    Details
    In: Molecular Ecology, Wiley, Vol. 27, No. 23 ( 2018-12), p. 4775-4786
    Abstract: 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.
    Type of Medium: Online Resource
    ISSN: 0962-1083 , 1365-294X
    URL: Issue
    URL: Article
    DOI: 10.1111/mec.2018.27.issue-23
    DOI: 10.1111/mec.14901
    RVK:
    WA 15000
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 2020749-9
    detail.hit.zdb_id: 1126687-9
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Temporal dynamics of active A rchaea in oxygen‐depleted zones of two deep lakes
    Wiley ; 2015
    In:  Environmental Microbiology Reports Vol. 7, No. 2 ( 2015-04), p. 321-329
    Details
    In: Environmental Microbiology Reports, Wiley, Vol. 7, No. 2 ( 2015-04), p. 321-329
    Abstract: Deep lakes are of specific interest in the study of archaeal assemblages as chemical stratification in the water column allows niche differentiation and distinct community structure. Active archaeal community and potential nitrifiers were investigated monthly over 1 year by pyrosequencing 16 S rRNA transcripts and genes, and by quantification of archaeal amoA genes in two deep lakes. Our results showed that the active archaeal community patterns of spatial and temporal distribution were different between these lakes. The meromictic lake characterized by a stable redox gradient but variability in nutrient concentrations exhibited large temporal rearrangements of the dominant euryarchaeal phylotypes, suggesting a variety of ecological niches and dynamic archaeal communities in the hypolimnion of this lake. Conversely, T haumarchaeota Marine Group I (MGI) largely dominated in the second lake where deeper water layers exhibited only short periods of complete anoxia and constant low ammonia concentrations. Investigations conducted on archaeal amoA transcripts abundance suggested that not all lacustrine T haumarchaeota conduct the process of nitrification. A high number of 16 S rRNA transcripts associated to crenarchaeal group C 3 or the M iscellaneous E uryarchaeotic G roup indicates the potential for these uncharacterized groups to contribute to nutrient cycling in lakes.
    Type of Medium: Online Resource
    ISSN: 1758-2229 , 1758-2229
    URL: Issue
    URL: Article
    DOI: 10.1111/emi4.2015.7.issue-2
    DOI: 10.1111/1758-2229.12251
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 2485218-1
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  • 3
    Online Resource
    Online Resource
    Influence of aphotic haloclines and euxinia on organic biomarkers and microbial communities in a thalassohaline and alkaline volcanic crater lake
    Wiley ; 2022
    In:  Geobiology Vol. 20, No. 2 ( 2022-03), p. 292-309
    Details
    In: Geobiology, Wiley, Vol. 20, No. 2 ( 2022-03), p. 292-309
    Abstract: Studies on microbial communities, and their associated organic biomarkers, that are found thriving in the aphotic euxinic waters in modern stratified ecosystems are scarce compared to those undertaken in euxinic photic zones. The Dziani Dzaha (Mayotte, Indian Ocean) is a tropical, saline, alkaline crater lake that has recently been presented as a modern analog of Proterozoic Oceans due to its thalassohaline classification (having water of marine origin) and specific biogeochemical characteristics. Continuous intense photosynthetic production and microbial mineralization keep most of the water column permanently aphotic and anoxic preventing the development of a euxinic (sulfidic and anoxic) photic zone despite a high sulfide/sulfate ratio and the presence of permanent or seasonal haloclines. In this study, the molecular composition of the organic matter in Lake Dziani Dzaha was investigated and compared to the microbial diversity evaluated through 16S rRNA gene amplicon sequencing, over two contrasting seasons (rainy vs. dry) that influence water column stratification. Depth profiles of organic biomarker concentrations (chlorophyll‐a and lipid biomarkers) and bacterial and archaeal OTU abundances appeared to be strongly dependent on the presence of aphotic haloclines and euxinia. OTU abundances revealed the importance of specific haloalkaliphilic bacterial and archaeal assemblages in phytoplanktonic biomass recycling and the biogeochemical functioning of the lake, suggesting new haloalkaline non‐phototrophic anaerobic microbial precursors for some of the lipid biomarkers. Uncultured Firmicutes from the family Syntrophomonadaceae (Clostridiales), and Bacteroidetes from the ML635J‐40 aquatic group, emerged as abundant chemotrophic bacterial members in the anoxic or euxinic waters and were probably responsible for the production of short‐chain n ‐alkenes, wax esters, diplopterol, and tetrahymanol. Halocline‐dependent euxinia also had a strong impact on the archaeal community which was dominated by Woesearchaeota in the sulfide‐free waters. In the euxinic waters, methanogenic Euryarchaeota from the Methanomicrobia, Thermoplasmata, and WSA2 classes dominated and were likely at the origin of common hydrocarbon biomarkers of methanogens (phytane, pentamethyl‐eicosenes, and partially hydrogenated squalene).
    Type of Medium: Online Resource
    ISSN: 1472-4677 , 1472-4669
    URL: Issue
    URL: Article
    DOI: 10.1111/gbi.v20.2
    DOI: 10.1111/gbi.12477
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2113509-5
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Evidence for an active rare biosphere within freshwater protists community
    Wiley ; 2015
    In:  Molecular Ecology Vol. 24, No. 6 ( 2015-03), p. 1236-1247
    Details
    In: Molecular Ecology, Wiley, Vol. 24, No. 6 ( 2015-03), p. 1236-1247
    Abstract: Studies on the active rare biosphere at the RNA level are mainly focused on Bacteria and Archaea and fail to include the protists, which are involved in the main biogeochemical cycles of the earth. In this study, the richness, composition and activity of the rare protistan biosphere were determined from a temporal survey of two lakes by pyrosequencing. In these ecosystems, the always rare OTU s represented 77.2% of the total OTU s and 76.6% of the phylogenetic diversity. From the various phylogenetic indices computed, the phylogenetic units ( PU s) constituted exclusively by always rare OTU s were discriminated from the other PU s. Therefore, the rare biosphere included mainly taxa that are distant from the reference databases compared to the dominant ones. In addition, the rarest OTU s represented 59.8% of the active biosphere depicted by r RNA and the activity (r RNA :r DNA ratio) increased with the rarity. The high r RNA :r DNA ratio determined in the rare fraction highlights that some protists were active at low abundances and contribute to ecosystem functioning. Interestingly, the always rare and active OTU s were characterized by seasonal changes in relation with the main environmental parameters measured. In conclusion, the rare eukaryotes represent an active, dynamic and overlooked fraction in the lacustrine ecosystems.
    Type of Medium: Online Resource
    ISSN: 0962-1083 , 1365-294X
    URL: Issue
    URL: Article
    DOI: 10.1111/mec.2015.24.issue-6
    DOI: 10.1111/mec.13116
    RVK:
    WA 15000
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 2020749-9
    detail.hit.zdb_id: 1126687-9
    SSG: 12
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    Contrasted ecological niches shape fungal and prokaryotic community structure in mangroves sediments
    Wiley ; 2019
    In:  Environmental Microbiology Vol. 21, No. 4 ( 2019-04), p. 1407-1424
    Details
    In: Environmental Microbiology, Wiley, Vol. 21, No. 4 ( 2019-04), p. 1407-1424
    Abstract: Mangroves are forest ecosystems located at the interface between land and sea where sediments presented a variety of contrasted environmental conditions (i.e. oxic/anoxic, non‐sulfidic/sulfidic, organic matter content) providing an ideal ecosystem to study microbial communities with niche differentiation and distinct community structures. In this work, prokaryotic and fungal compositions were investigated during both wet and dry seasons in New Caledonian mangrove sediments, from the surface to deeper horizons under the two most common tree species in this region ( Avicennia marina and Rhizophora stylosa) , using high‐throughput sequencing. Our results showed that Bacteria and Archaea communities were mainly shaped by sediment depth while the fungal community was almost evenly distributed according to sediment depth, vegetation cover and season. A detailed analysis of prokaryotic and fungal phyla showed a dominance of Ascomycota over Basidiomycota whatever the compartment, while there was a clear shift in prokaryotic composition. Some prokaryotic phyla were enriched in surface layers such as Proteobacteria , Euryarchaeota while others were mostly associated with deeper layers as Chloroflexi , Bathyarchaeota , Aminicenantes . Our results highlight the importance of considering fungal and prokaryotic counterparts for a better understanding of the microbial succession involved in plant organic matter decomposition in tropical coastal sediments.
    Type of Medium: Online Resource
    ISSN: 1462-2912 , 1462-2920
    URL: Issue
    URL: Article
    DOI: 10.1111/emi.2019.21.issue-4
    DOI: 10.1111/1462-2920.14571
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2020213-1
    SSG: 12
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