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Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
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Microbial Response to Experimentally Controlled Redox Transitions at the Sediment Water Interface
Katharina Frindte1, Martin Allgaier2, Hans-Peter Grossart3,4
1Department of Soil Science, Institute for Crop Science and Resource Conservation (INRES), University of Bonn, Nußallee 13, Bonn, Germany.
Plos One
|November 25, 2015
Summary
Microbial communities in lake sediments shift dramatically with changing oxygen levels, impacting key processes like nitrate and sulfate reduction. These redox transitions reveal dynamic interactions between geochemistry and microbial function.
Area of Science:
- Environmental microbiology
- Geochemistry
- Limnology
Background:
- The sediment-water interface in freshwater lakes exhibits steep chemical gradients due to physical, chemical, and microbial interactions.
- Oxygen depletion in upper sediments necessitates alternative electron acceptors, influencing microbial processes.
Purpose of the Study:
- To investigate microbial activity shifts during simulated aerobic to anaerobic transitions at the sediment-water interface.
- To correlate hydrochemical changes with microbial community and functional gene expression dynamics.
Main Methods:
- Time-series mesocosm experiment simulating redox transitions.
- Monitoring of overlying water hydrochemistry.
- Novel sediment bacterial sampling strategy.
- Denaturing Gradient Gel Electrophoresis (DGGE) analysis for microbial community and gene expression.
Main Results:
- Nitrate availability and the onset of sulfate reduction significantly impacted functional gene expression during oxic-heterotrophic to sulfate-reducing transitions.
- Evidence of anaerobic methane oxidation coupled with NOx was observed.
- Redox changes correlated with microbial activity and gene expression for sulfate and nitrite reduction, with minor shifts in methanogenesis and methanotrophy.
Conclusions:
- High-frequency chemical and molecular data provide novel insights into the temporal dynamics of microbial activity and redox transitions at the sediment-water interface.
- Redox state is a critical driver of microbial community structure and function in lake sediments.
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