My research interest is focused on interactions between different organisms in the marine environment as well as their involvement in feedback mechanisms to the environment. Project: Biogeochemical cycling of N-osmolytes in the surface ocean Osmolytes such as dimethylsulfoniopropionate (DMSP), choline or glycine betaine (GBT) enable marine organisms to cope better with the stressful conditions found in oceanic ecosystems. Consequently, these compounds accumulate inside their cells. Upon their occasional release into the environment, osmolytes can constitute an important nutrient source for many members of the marine microbial community. Present knowledge of osmolyte biogeochemical cycling, however, is solely focused on the sulphur-containing DMSP, thereby overlooking nitrogen-containing osmolytes such as choline or GBT. My role in this project is to explore metabolic processes involved in N-osmolyte degradation using the cosmopolitan marine alphaproteobacterium Ruegeria pomeroyi as a model organisms. Further, I analyse microbial uptake and respiration in natural surface seawater from Station L4 of the Western Channel Observatory and try to define the parameter mostly influencing annual patterns. In addition, I am targeting microbes that metabolise N-osmolytes in the natural community using a stable isotope probing approach of a spring and summer bloom. This project is part of an UK Natural Environment Research Council grant on