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Coherent dynamics and association networks among lake bacterioplankton taxa
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
2012 (English)In: The ISME Journal: multidisciplinary journal of microbial ecology, ISSN 1751-7362, Vol. 6, no 2, 330-342 p.Article in journal (Refereed) Published
Abstract [en]

Bacteria have important roles in freshwater food webs and in the cycling of elements in the ecosystem. Yet specific ecological features of individual phylogenetic groups and interactions among these are largely unknown. We used 454 pyrosequencing of 16S rRNA genes to study associations of different bacterioplankton groups to environmental characteristics and their co-occurrence patterns over an annual cycle in a dimictic lake. Clear seasonal succession of the bacterioplankton community was observed. After binning of sequences into previously described and highly resolved phylogenetic groups (tribes), their temporal dynamics revealed extensive synchrony and associations with seasonal events such as ice coverage, ice-off, mixing and phytoplankton blooms. Coupling between closely and distantly related tribes was resolved by time-dependent rank correlations, suggesting ecological coherence that was often dependent on taxonomic relatedness. Association networks with the abundant freshwater Actinobacteria and Proteobacteria in focus revealed complex interdependencies within bacterioplankton communities and contrasting linkages to environmental conditions. Accordingly, unique ecological features can be inferred for each tribe and reveal the natural history of abundant cultured and uncultured freshwater bacteria.

Place, publisher, year, edition, pages
2012. Vol. 6, no 2, 330-342 p.
Keyword [en]
freshwater, 454 pyrosequencing, 16S rRNA, phylogenetic tribes, bacteria
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:uu:diva-171679DOI: 10.1038/ismej.2011.113ISI: 000300984200011OAI: oai:DiVA.org:uu-171679DiVA: diva2:512097
Available from: 2012-03-26 Created: 2012-03-25 Last updated: 2016-04-22Bibliographically approved
In thesis
1. Drivers of Population Dynamics in Bacterioplankton: Spotlight on Alphaproteobacteria and its dominant SAR11 Lineage
Open this publication in new window or tab >>Drivers of Population Dynamics in Bacterioplankton: Spotlight on Alphaproteobacteria and its dominant SAR11 Lineage
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Bacteria are mediators of biogeochemical cycles and are in this way vital for maintaining life on earth. Their distribution, abundance and functioning are driven by environmental heterogeneity and dynamic change in abiotic and biotic factors. Both, freshwater lakes and oceans play central roles in the global carbon cycle and bacteria in these systems perform many services for the ecosystems, such as the transfer of organic carbon from primary producers to higher trophic levels. With estimated relative abundances up to 50% of the total bacterioplankton, the Alphaproteobacteria lineage SAR11 is the most abundant group of aquatic bacteria. It is globally distributed and can be partitioned into multiple sub-clades, one of which is exclusive to freshwaters. Until recently, the distribution, abundance and ecological role of this freshwater SAR11 named LD12 was unknown. The aim of the thesis was to study the drivers and mechanisms that influence the dynamics of aquatic bacterial communities in general and the SAR11 and LD12 groups in particular. The thesis consists of environmental surveys of a mesotrophic Lake Erken and the western Southern Ocean, an experiment and a data-mining exercise to reveal the phylogenetic structure of the SAR11 lineage on various temporal and spatial scales. The analysis of a long-term bacterioplankton community survey in lake Erken provided insights about the dynamics of the entire bacterial community and the LD12 population over an annual cycle. The results demonstrate that LD12 can be an equally abundant member of freshwater communities as marine SAR11 in oceans. LD12 featured strong seasonality and was positively coupled to environmental conditions indicative for an oligotrophic lifestyle. LD12 as well as other dominant lake bacterioplankton also maintained stable populations throughout spatial and temporal varying environments, but at high phylogenetic resolution, habitat preferences were revealed, particularly in response to oxygen concentrations. The later was not the case in LD12 as a single ribotype dominated. This is in stark contrast to the habitat partitioning with light availability, depth and water masses observed for marine SAR11 subclades in the Southern Ocean. The global data-mining corroborated that LD12 as a group was much less diverse than SAR11 furthermore, suggesting that the marine-freshwater barrier acted as a population bottleneck. My work shows that bacterial populations can respond in very different ways to environmental drivers, highlight the importance of highly resolved temporal and spatial scales as well as the need for high phylogenetic resolutions to target ecologically coherent populations.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 54 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1230
Keyword
bacterial community dynamics, Alphaproteobacteria, SAR11, LD12, Southern Ocean, lakes
National Category
Ecology
Research subject
Biology with specialization in Limnology
Identifiers
urn:nbn:se:uu:diva-245072 (URN)978-91-554-9172-7 (ISBN)
Public defence
2015-04-10, Fries-salen, Evolutionsbiologiskt Centrum (EBC), Norbyvägen 14, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2015-03-19 Created: 2015-02-24 Last updated: 2015-04-17

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Eiler, AlexanderHeinrich, FriederikeBertilsson, Stefan

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