Research
Theme 1 & 2
www.darwincenter.nl
Project 1101

The Role of sulfate-reducing bacteria in controlling sediment phosphorus preservation in sediments overlain by anoxic bottom waters
Project leader: Prof. dr. H. J. Laanbroek
Researcher(s): Drs. A. K. Steenbergh
Starting date: 1-okt-07

Abstract
Sulfate reduction can account for > 90% of organic carbon mineralization in sediments overlain by anoxic bottom waters. Several studies have confirmed that under these conditions, P release from organic matter in the sediments is enhanced and can be quantitatively much more important than sulfide-induced release of P from Fe-oxides. It is hypothesized that the metabolic activities of the sulfatereducing bacteria (SRB) largely determine the fate of the organic P deposited in sediments under anoxic bottom waters. To test this, the relations between the kinetics of sulfate reduction and P-release, and the metabolic activity of the sulfate-reducing microbial community will be established in a series of laboratory experiments with slices from well-studied modern day and ancient anoxic sediments. Specific attention will be paid to the effects of flow or refreshment rate on these relations. To take the whole active SRB community into account, the total diversity in all sediment types will be determined by creating clone libraries based on the dsrAB gene, which is specific for all SRB, in combination with the in situ incorporation of 13C-labelled organic compounds. Finally, a comparison will be made with the activity and P-release of aerobic microorganisms in natural sediments.

Publications
Anne K. Steenbergh, Marion M. Meima, Miranda Kamst & Paul L.E. Bodelier (2010). Biphasic kinetics of amethanotrophic community is a combination of growth and increased activityper cell. FEMS Microbiol Ecol71: 12-12.
Darwin Center authors: Bodelier P. L. E., Steenbergh A. K.

Anne K. Steenbergh, Paul L. E. Bodelier, Hans L. Hoogveld, Caroline P. Slomp, and Hendrikus J. Laanbroek (2011). Phosphatases relieve carbon limitation of microbial activity in Baltic Sea sediments along a redox-gradient. Limnology & Oceanography56(6): 2018-2026.
Darwin Center authors: Bodelier P. L. E., Laanbroek H. J., Slomp C. P., Steenbergh A. K.

Anne Steenbergh (2012). The microbial control of phosphorus fluxes in marine sediments.
Darwin Center authors: Steenbergh A. K.