| 1. |
- Battin, Tom J., et al.
(författare)
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The boundless carbon cycle
- 2009
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 2:9, s. 598-600
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Besemer, Katharina, et al.
(författare)
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Unraveling assembly of stream biofilm communities
- 2012
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Ingår i: The ISME Journal: multidisciplinary journal of microbial ecology. - : Springer Science and Business Media LLC. - 1751-7362. ; 6:8, s. 1459-1468
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Tidskriftsartikel (refereegranskat)abstract
- Microbial biofilms assemble from cells that attach to a surface, where they develop into matrix-enclosed communities. Mechanistic insights into community assembly are crucial to better understand the functioning of natural biofilms, which drive key ecosystem processes in numerous aquatic habitats. We studied the role of the suspended microbial community as the source of the biofilm community in three streams using terminal-restriction fragment length polymorphism and 454 pyrosequencing of the 16S ribosomal RNA (rRNA) and the 16S rRNA gene (as a measure for the active and the bulk community, respectively). Diversity was consistently lower in the biofilm communities than in the suspended stream water communities. We propose that the higher diversity in the suspended communities is supported by continuous inflow from various sources within the catchment. Community composition clearly differed between biofilms and suspended communities, whereas biofilm communities were similar in all three streams. This suggests that biofilm assembly did not simply reflect differences in the source communities, but that certain microbial groups from the source community proliferate in the biofilm. We compared the biofilm communities with random samples of the respective community suspended in the stream water. This analysis confirmed that stochastic dispersal from the source community was unlikely to shape the observed community composition of the biofilms, in support of species sorting as a major biofilm assembly mechanism. Bulk and active populations generated comparable patterns of community composition in the biofilms and the suspended communities, which suggests similar assembly controls on these populations.
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| 3. |
- Bottacin-Busolin, Andrea, 1980-, et al.
(författare)
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Effects of Streambed Morphology and Biofilm Growth on the Transient Storage of Solutes
- 2009
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:19, s. 7337-7342
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Tidskriftsartikel (refereegranskat)abstract
- Microbial biofilms are the prime site of nutrient and contaminant removal in streams. It is therefore essential to understand how biofilms affect hydrodynamic exchange, solute transport and retention in systems where geomorphology and induced hydrodynamics shape their growth and structure. We experimented with large-scale streamside flumes with streambed landscapes constructed from graded bedforms of constant height and wavelength. Each flume had a different bedform height and was covered with a layer of gravel as substratum for benthic microbial biofilms. Biofilms developed different biomass and physical structures in response to the hydrodynamic conditions induced by the streambed morphology. Step injections of conservative tracers were performed at different biofilm growth stages. The experimental breakthrough curves were analyzed with the STIR model, using a residence time approach to characterize the retention effects associated with biofilms. The retained mass of the solute increased with biofilm biomass and the biofilm-associated retention was furthermore related to bedform height We tentatively relate this behavior to biofilm structural differentiation induced by bed morphology, which highlights the strong linkage between geomorphology, hydrodynamics, and biofilms in natural streams and provide important clues for stream restoration.
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| 4. |
- Hoedl, Iris, et al.
(författare)
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Voronoi Tessellation Captures Very Early Clustering of Single Primary Cells as Induced by Interactions in Nascent Biofilms
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:10, s. e26368-
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Tidskriftsartikel (refereegranskat)abstract
- Biofilms dominate microbial life in numerous aquatic ecosystems, and in engineered and medical systems, as well. The formation of biofilms is initiated by single primary cells colonizing surfaces from the bulk liquid. The next steps from primary cells towards the first cell clusters as the initial step of biofilm formation remain relatively poorly studied. Clonal growth and random migration of primary cells are traditionally considered as the dominant processes leading to organized microcolonies in laboratory grown monocultures. Using Voronoi tessellation, we show that the spatial distribution of primary cells colonizing initially sterile surfaces from natural streamwater community deviates from uniform randomness already during the very early colonisation. The deviation from uniform randomness increased with colonisation - despite the absence of cell reproduction - and was even more pronounced when the flow of water above biofilms was multidirectional and shear stress elevated. We propose a simple mechanistic model that captures interactions, such as cell-to-cell signalling or chemical surface conditioning, to simulate the observed distribution patterns. Model predictions match empirical observations reasonably well, highlighting the role of biotic interactions even already during very early biofilm formation despite few and distant cells. The transition from single primary cells to clustering accelerated by biotic interactions rather than by reproduction may be particularly advantageous in harsh environments - the rule rather than the exception outside the laboratory.
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| 5. |
- Philippot, Laurent, et al.
(författare)
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The ecological coherence of high bacterial taxonomic ranks
- 2010
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Ingår i: Nature Reviews Microbiology. - : Springer Science and Business Media LLC. - 1740-1526 .- 1740-1534. ; 8:7, s. 523-529
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Forskningsöversikt (refereegranskat)abstract
- The species is a fundamental unit of biological organization, but its relevance for Bacteria and Archaea is still hotly debated. Even more controversial is whether the deeper branches of the ribosomal RNA-derived phylogenetic tree, such as the phyla, have ecological importance. Here, we discuss the ecological coherence of high bacterial taxa in the light of genome analyses and present examples of niche differentiation between deeply diverging groups in terrestrial and aquatic systems. The ecological relevance of high bacterial taxa has implications for bacterial taxonomy, evolution and ecology.
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| 6. |
- Prairie, Yves T., et al.
(författare)
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Greenhouse Gas Emissions from Freshwater Reservoirs : What Does the Atmosphere See?
- 2018
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Ingår i: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 21:5, s. 1058-1071
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Tidskriftsartikel (refereegranskat)abstract
- Freshwater reservoirs are a known source of greenhouse gas (GHG) to the atmosphere, but their quantitative significance is still only loosely constrained. Although part of this uncertainty can be attributed to the difficulties in measuring highly variable fluxes, it is also the result of a lack of a clear accounting methodology, particularly about what constitutes new emissions and potential new sinks. In this paper, we review the main processes involved in the generation of GHG in reservoir systems and propose a simple approach to quantify the reservoir GHG footprint in terms of the net changes in GHG fluxes to the atmosphere induced by damming, that is, ´€˜what the atmosphere sees’. The approach takes into account the pre-impoundment GHG balance of the landscape, the temporal evolution of reservoir GHG emission profile as well as the natural emissions that are displaced to or away from the reservoir site resulting from hydrological and other changes. It also clarifies the portion of the reservoir carbon burial that can potentially be considered an offset to GHG emissions.
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