Ammonia oxidizing archaea play an important role in the nitrogen cycle on Earth. In order to oxidize ammonia to nitrite, the single-celled microorganisms require copper. In the course of a Marie Curie Fellowship, microbiologist Carolina Reyes examines strategies how archaea take-up copper from soils and water. The project arises from the Environmental Sciences Research Network of the University of Vienna and is based on cooperation between scientists in the fields of environmental geosciences (led by Stephan Krämer) and microbiology (led by Christa Schleper).