Microbially mediated redox processes in aquatic systems with micro-niches

  • Jakobsen, Rasmus (Project Participant)
  • Smets, Barth F. (Project Participant)

Project Details


Sub-domains in the mm-µm range are often termed micro-niches and are present in many systems e.g. porous media (oil and groundwater reservoirs), water supply and waste water systems. If reactants are exclusive to a micro-niche and reaction rates are fast compared to diffusive transport, the chemical environment in the micro-niche will be different from the bulk environment and may imply that also the microbe(s) residing in the micro-niche are different from the microbes in the bulk system. This micro-scale arrangement will significantly affect the microbial ecology of a natural or technical system and the ecosystems ability to adapt to changing conditions on a bulk scale, e.g. changing redox conditions in soils. The micro-niches may also have adverse as well as beneficial effects. Adverse effects could be sustaining pathogens by providing “hiding places” in e.g. water supply systems or housing sulfate reducing bacteria and organic matter resulting in sulfide in the supplied water. Benefits may occur when locally lowered redox conditions inside micro-niches containing reductants enable microbially mediated degradation of chlorinated ethenes that would otherwise not be degraded. These examples show that the effects of micro-niches on the microbial ecology may determine important issues such as the mobility of redox sensitive compounds in soils, supplied water quality and the success of groundwater remediation schemes. In spite of this the quantitative circumstances that make micro-niches problematic or beneficial are not known in any detail. How are the micro-niches populated, how do they sustain microbial reactions, how small can these micro-niches be and still house viable microbial populations ? These are the type of questions that need to be answered if we are to exploit or avoid the effects of the micro-niches present in most systems.
The project will use micro-models etched in fused silica mounted in flow cells, in vivo fluorescent protein labeling of specific microbes and advance individual based modeling to include the geochemistry of the surroundings.
Effective start/end date03/08/200929/07/2011


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