Novel ecosystem assessment

Nitrogen fixation is the main source of nitrogen in the open ocean and a crucial part of primary production at the base of the foodweb. This in turn is linked to the exchange of carbon dioxide between the atmosphere and the sea, where it is consumed during biomass production and emitted during respiration.

Iron can be a limiting nutrient for nitrogen fixation and/or primary production and is supplied to the open ocean mainly via dust deposition. A reflection of increased desertification and changing land use, global dust deposition is therefore of international interest.

With EU funding, the 'Proteomic approaches to assess the oceanic nitrogen biogeochemistry' (PROTEON) project is developing a unique high-throughput approach to link the metabolic activity of organisms to their identity in a given sample. The analysis is based on the proteins and the natural carbon and nitrogen isotopes present in a model system.

Two bacterial cultures and a sample from a meromictic lake (that has layers of water that do not intermix) are under scrutiny to develop the high-throughput approach. Project work to date has seen the collection of metagenomics data from Mahoney Lake in Canada. A resulting manuscript on the microbial community and the sulphur cycle has been published in Geobiology.

Researchers have successfully developed the method, protein stable isotope fingerprinting (P-SIF), for carbon isotopes. Nitrogen isotopes proved more problematic, but work is continuing to resolve the technical difficulties. Nevertheless, details of the work were published in the peer-reviewed journal Analytical Chemistry. Protein extraction from seawater is also on the agenda for further resolution, and the researchers will work on increasing the amount of protein for input into P-SIF.

The newly developed P-SIF promises to be a valuable tool in evaluation of the link between marine microorganisms and their role in the ecosystem. The novel method will allow the study of previously unknown microbes that may be crucial in the understanding of biogeochemical processes in the environment.

Translation of skills fostered and developed in PROTEON to the European Research Area (ERA) means that globally relevant issues such as land-use change can be assessed. The new methods of environment assessment could enhance European research excellence and increase the competitiveness of European research.