DOUBLECHECK · Double-check of dissimilatory nitrate reduction to either ammonium or dinitrogen in aquatic habitats
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-02-01 → 2008-01-31
- EU contribution
- €40,000
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - DOUBLECHECK (Double-check of Dissimilatory Nitrate Reduction to either Ammonium or Dinitrogen in Aquatic Habitats)
The project focused on the comparative investigation of denitrification and dissimilatory nitrate reduction to ammonium (DNRA), two benthic microbial processes of great importance for nitrogen cycling in aquatic ecosystems. The metabolic control of both processes was simultaneously studied in benthic gradient chambers in which natural conditions, i.e. the microenvironment for sediment bacteria, are much better represented than in the commonly used slurry assays. By implementing a newly developed gel-probe technique in this experimental set-up, it was possible for the first time to determine the vertical distribution of both processes relative to each other. It was proven that the two processes can coexist in one and the same sediment by means of spatial separation along vertical nitrate and sulfide gradients. We can thereby revise the current notion that in a given environment only one of the two processes will dominate due to the competitive exclusion principle. It was also demonstrated that denitrifying sediments can be shifted towards DNRA by increasing the sulfide supply from deep sediment strata. This implies that the deterioration of aquatic ecosystems due to organic pollution can trigger the intensification of eutrophication due to nitrogen compounds (i.e., ammonium produced by DNRA) that are not eliminated from the ecosystem in the form of gas (i.e., dinitrogen produced by denitrification).
Data: CORDIS, © European Union
Project objective
The proposed project focuses on the so far neglected comparative investigation of denitrification and DNRA (Dissimilatory Nitrate Reduction to Ammonium), two benthic microbial processes of great importance for nitrogen cycling in aquatic ecosystems.We aim at moving DNRA more into the spotlight, because:(1) its metabolic control and phylogenetic diversity is understudied compared to denitrification; and(2) its environmental importance will increase relative to denitrification due to the excessive water use in aquaculture and desalination.Anthropogenic and environmental factors that change the partitioning between the two processes will also affect the ratio of nitrogen removal (denitrification) and nitrogen retention (DNRA) from and within the ecosystem. Therefore, we expect that a better understanding of the metabolic control and phylogenetic diversity of DNRA will aid in developing management strategies for handling nitrogenous pollution of aquatic ecosystems.In an integrated approach using the contemporary techniques of microbial ecology we aim at:(1) measuring rates of denitrification & DNRA simultaneously and at high spatial resolution in marine sediments, aquaculture and desalination systems;(2) determining community structure and gene expression of denitrifying & DNRA-performing bacteria in natural sediments; and(3) correlating rates with presence & metabolic status of denitrifying & DNRA-performing bacteria, and with spatial gradients of environmental factors (H2S & T OC).The field investigations will be complemented by laboratory incubations in which the short-term metabolic response and the long-term community shifts of denitrifying & DNRA-performing bacteria can be studied. Additionally, denitrifying & DNRA-performing strains will be isolated from the field-collected samples and screened for co-occurrence of functional genes of both metabolic pathways.
Original text from CORDIS.
Participants
- MAX-PLANCK-GESELLSCHAFT ZUR FOERDERUNG DER WISSENSCHAFTEN E.V./MAX-PLANCK-INSTITUT FUER MARINE MIKROBIOLOGIE · MUENCHENCoordinatorCity levelGermany
Links
Data: CORDIS, © European Union