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Bacterial communities shaping the redox environment in top-layer sediments of an oligotrophic high latitude lake
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, Science for Life Laboratory, SciLifeLab.ORCID iD: 0000-0002-4265-1835
(English)Manuscript (preprint) (Other academic)
Keyword [en]
Electromicrobiology, Bacteria, Microsensors, Redox potential, Lake Sediments
National Category
Biological Sciences
Research subject
Biology with specialization in Limnology
Identifiers
URN: urn:nbn:se:uu:diva-263205OAI: oai:DiVA.org:uu-263205DiVA: diva2:857281
Available from: 2015-09-28 Created: 2015-09-28 Last updated: 2017-01-25Bibliographically approved
In thesis
1. Microbial adaptations and controlling mechanisms of surface-associated microhabitat heterogeneity in aquatic systems
Open this publication in new window or tab >>Microbial adaptations and controlling mechanisms of surface-associated microhabitat heterogeneity in aquatic systems
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Habitat heterogeneity is a driving factor for speciation and ecosystem functioning and is well studied in macro-ecology. Yet our understanding of microbial adaptations, and governing processes is incomplete. The here presented thesis aims at giving us a better understanding of patterns in micro-heterogeneity, and microbial adaptations to such heterogeneity with particular focus on surface-dominated, aquatic habitats. The most prominent microbial adaptation to surface associated mode of life is biofilm formation. Biofilms rely heavily on type IV pili. These pili systems are well studied in Bacteria, but largely unknown in Archaea. Therefore, the first part of this thesis focuses on resolving genetic and structural feature of the type IV like aap-pilus of the thermo-acidophilic Sulfolobus acidocaldarius. We found the aap-pilus to be indispensible for biofilm formation, and to be unparalleled in variability of its quaternary structure and cross regulation with other filaments. The second part of this thesis investigates particle colonization in the water column, focusing on diatoms as a model system, allowing an in situ assessment of different stages of particle colonization, and potential particle-specificity of the associated bacterial community. Opposing reports from marine systems, we did not observe diatom-specificity in the associated bacterial community. Instead we found bacterial community subsets, one likely originating from sediment resuspension, and the other being controlled by biofilm-forming populations (e.g. Flexibacter), able to attach to newly formed particle surfaces and subsequently facilitate secondary colonization by other bacteria. Finally, the habitat heterogeneity in top-layers of lake sediments were investigated in experimental microcosms. Cell-specific oxygen consumption rates were determined, to assess microbial activity across different scales. Individual activity rates differed strongly across all investigated scales, likely due to spatially heterogeneous distribution of nutrients with differing quality. Vice versa, the influence of microbial activity on micro-habitat-heterogeneity was investigated. We correlated sediment redox-state with bacterial community composition and populations. Our results indicate that habitat heterogeneity is generally beneficial for microorganism, and greater heterogeneity results in greater bacterial diversity. However, this heterogeneity-diversity relationship is limited and microorganisms actively stabilize their immediate redox environment to a preferred, community-specific, stable state, if cell abundances exceed a minimum threshold.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 69 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1296
Keyword
microbial habitat heterogeneity
National Category
Biological Sciences
Research subject
Biology with specialization in Limnology
Identifiers
urn:nbn:se:uu:diva-263206 (URN)978-91-554-9351-6 (ISBN)
Public defence
2015-11-20, Ekman Salen, Norbyvägen 14, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2015-10-27 Created: 2015-09-28 Last updated: 2015-11-10

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Jeske, Jan TorstenBertilsson, Stefan

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