Forskningsområder

I am working in the field of biogeochemistry and microbial ecology to understand the dynamic between biological evolution, element cycles and how this influences Earth surface changes today and through Earth history.

My research has right now a focus on following topics:

1. Environmental proteomics.
2. The microbial sulfur cycle and stable sulfur isotopes.
3. The microbial sulfur and methane cycle of brine seeps in the Gulf of Mexico.
4. Biogeochemical measurements of marine and freshwater sediments.
5. Cell specific activity of microorganisms in natural environments.
6. Fieldwork

Environmental proteomics . Primary production in the meromictic Lake Cadagno, Switzerland, is dominated by anoxygenic photosynthesis. Cells from four positions in the water column were used for comparative analysis of the Chl. clathratiforme proteome in order to investigate changes in protein composition in response to the chemical and physical gradient in their environment, with special focus on how the bacteria survive in the dark. Although metagenomic data is not available for Lake Cadagno, proteome analysis was possible based on the completely sequenced genome of an isolated strain of Chl. clathratiforme. Using LC MS/MS we identified 1321 Chl. clathratiforme proteins in Lake Cadagno and quantitatively compared 621 of these in the four samples. From the proteome analysis we were able to show that Chl. clathratiforme in the photic zone contains enzymes for fixation of N2 and the complete oxidation of sulfide to sulfate while these processes are probably not active in the dark. Based on the observed protein compositions we have constructed possible pathways for C, N and S-metabolism in Chl. clathratiforme.

The microbial sulfur cycle and stable sulfur isotopes. We conduct various different experiments to understand the regulation of the sulfur isotope fractionation during sulfate reduction. The results are used to understand the stable sulfur isotope record from sediments deposit today and through Earth history.

The microbial sulfur and methane cycle of brine seeps in the Gulf of Mexico. At the seafloor of the Gulf of Mexico there are brines seeps where hot high saline water is flowing from the deep subsurface to the seafloor creating lake-like features. The heavy saltwater is lying as oxygen free brine pools at the bottom of the ocean having particular no exchange with the overlying seawater. The brines are laden with energy-rich compounds, which is the reason that the brine pools are not dead but contain high concentrations of microorganisms and their productivity supports a rich animal life. We wish to study the microbial and chemical processes associated the sulfur cycle of these brine seeps and study how these processes affect the surrounding environment, and stable isotope probing of DNA and RNA should identify the most active sulfate reducing bacteria. We also want to measure the stable sulfur isotope compositions of the most important sulfur compounds and understand how these signals are produced. These data will be used to understand the sulfur isotope record from sulfur deposits through Earth history. The project will be connected the American Seafloor Brine Seep Microbial Observatory lead by Samantha Joye, Georgia University Athens, USA.

Biogeochemical measurements of marine and freshwater sediments. I use various techniques to measure the microbial processes in marine and freshwater systems:

¹⁴C-carbonate incubation for primary production measurements.
Microelectrodes for oxygen consumption.
Bag incubations and flux measurements for total carbon consumption.
Bag incubation for measuring iron reduction rate
³⁵S-sulfat radio labeled technique for sulfate reduction rate.

Cell specific activity of microorganisms in natural environments. I use various methods to identify the cell specific activity of microorganisms: Microautoradiography in combination with in-situ fluorescence hybridization (MAR-FISH), stable isotope probing of DNA and RNA (SIP) and proteomics.

Fieldwork. I have lead several international expeditions to sulfide and iron rich lakes in Switzerland and Spain. I have also participated in fieldwork going to Solar Lake; Egypt; Eilat, Israel; Yellowstone National Park, USA; Black Sea and Galathea 3 Expedition to the oxygen minimum zone out of Chile and Peru.

Right now I am planning a field course in Geobiology for master students on Iceland. This course will take place in August 2011.

Arbejdsopgaver

Lektor

CV

Download CV (pdf)

Stilling

Lektor (tidsbegrænset)

Uddannelse

• 1993, M.Sc. (cand. scient.) i biologi, Århus Universitet.
• 1997, Ph.D. i biogeokemi og mikrobiel økologi, Bremen Universitet, Tyskland.

Ansættelser

• 1994 – 1997, Ph. D. student, Afdeling for Biogeokemi, Max Planck Institut für Marine Mikrobiologie, Bremen, Tyskland.

• 1997, post doc, Afdeling for Biogeokemi, Max Planck Institut für Marine Mikrobiologie, Bremen, Tyskland.

• 1998 – 2003, forsknings adjunkt, Dansk Center for Klima og Biogeokemiske Kredsløb, Biologisk Institut, Syddansk Universitet

• siden 2003, lektor, Biologisk Institut, Syddansk Universitet.

Videnskabelige udlandsophold:

• 1998, c/o Theo A. Hansen, Microbial Physiology, University of Groningen, Holland, 3 uger
• 2001, c/o David J. Des Marais, Exobiology Branch, NASA Ames Research Center, California, USA, 1 år.
• 2006, c/o Jeppe Lund Nielsen, Department for Biotechnology, Chemistry and Environmental Engineering, Ålborg Universitet, 2 uger
• 2007, c/o Natuschka M. Lee, Department of Microbiology, Technical University Munich, Freising, Tyskland, en uge.

Undervisning

• Microbiel Økologi (BB15)
• Biologisk Oceanografi (BB86)
• Kystnære pelagiske processer (BB87)
• Science projekter (NAT501)
• Biologiseminarer (BB814)

Administration:

• 2003-2006: Koordinator for den internationale master uddannelse Biologisk Oceanografi ved Syddansk Universitet

Tilknytninger

• Nordisk Center for Jordens Udvikling (NordCEE) - Lektor

Publikationer

Aktiviteter