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Content archived on 2024-05-29

The ecological roles of planktonic archaeal and bacterial ammonia oxidizers in the oceanic nitrogen cycle

Objective

This proposal aims at determining the role of planktonic ammonia-oxidizing archaea (AOA) versus ammonia-oxidizing bacteria (AOB) in the marine pelagic environments that are critical for global nitrogen cycle. This will be accomplished by using a combination of conventional enrichment techniques with recently developed molecular methods.

By means of a modified catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) method and quantitative PCR technology, the abundance of the major prokaryotic groups of ammonia-oxidizers (AOB and AOA) will be determined in two coastal ecosystems (Irish and Black Sea) as compared to meso- and bathypelagic deep water of the Atlantic ocean.

Combining this method with micro-autoradiography we will be able to determine inorganic N uptake of individual cells and relate this to the measurements on bulk archaeal and prokaryotic community.

AOB and AOA distribution and diversity will be determined via terminal-restriction fragment polymorphism analysis of ammonia monooxygenase (amoA) genes combined with construction of environmental DNA bank for each sampling site.

Specific new oligonucleotide probes for dominant ammonia-species will be designed and applied in the MICRO-FISH assay to determine interspecific differences in the utilization and activity of coastal and deep water ammonia-oxidizers.

Seawater batch cultures with coastal and deep ocean water will be used to isolate new AOA and AOB species using a laboratory enrichment and cultivation approach. The obtained pure culture and environmental samples will be used for quantitative analysis of archaeal and bacterial nitrification amoA and denitrification nirK and norB gene expression in microcosms experiments.

While the AOB and AOA genes and enzymes involved in ammonia oxidation and N2O production have been recently isolated, the extent to which AOA and AOB are actively oxidizing ammonia and/or producing N2O under varying environmental conditions has never been studied before.

Fields of science (EuroSciVoc)

Keywords

Topic(s)

Call for proposal

FP6-2005-MOBILITY-5
See other projects for this call

Funding Scheme

EIF - Marie Curie actions-Intra-European Fellowships

Coordinator

UNIVERSITY OF LIVERPOOL
EU contribution
No data
Total cost
No data