My research interests focus on identifying and quantifying the contribution of novel marine microorganisms to fixation of atmospheric nitrogen into bioavailable nitrogen.
In vast oceanic areas, primary production is limited by the availability of fixed inorganic nitrogen (DIN=NO3-+NO2-+NH4+). The main source of DIN in the Ocean is microbially mediated N2-fixation. Traditionally N2 fixation has been attributed to diazotrophs such as Trichodesmium, but recent discoveries indicate that other microbes contribute significantly to the fixed nitrogen pool. The main methods used in my research are Catalyzed Reporter Deposition-Fluorescence in situ hybridization (CARD-FISH) and Halogen In Situ Hybridization-Secondary Ion Mass Spectroscopy (HISH-SIMS), which I use to identify novel nitrogen fixing organisms in environmental samples from oligotrophic marine waters (such as the subtropical Atlantic). I also use combinations of 15N2 isotope labelling assays and HISH-SIMS to quantify N2 fixation rates under different substrate conditions.