Nitrogen (N) is an essential macronutrient for all living beings and a key process in the nitrogen cycle is nitrification, a two-step pathway oxidizing ammonia over nitrite to nitrate. Throughout the global ocean, however, the availability of compounds like ammonia and nitrate is not consistent. Contrary, the distribution of dissolved organic nitrogen (DON) is rather homogenous.
My research is about nitrifiers and their usage of DON compounds as substrates (e.g. N source and/or energy source). I am particularly interested in ammonium-limited ocean regions, where the relative importance of DON is high.
My main techniques include:
- Stable isotope incubations to quantify the bulk oxidation rates
- Visualisation of microorganisms with CARD-FISH
- Analysis of metagenomes and metatranscriptomes to investigate the genetic potential of the nitrifiers
- nanoSIMS measurements to quantify uptake of substrates by nitrifiers