Environmental viruses heavily influence the genetic diversity and ecology of microbial communities and thus exert control on biogeochemical cycling. This has been exemplified for the carbon cycle in concepts like the viral shunt and the viral shuttle. However, very little is known how viruses modulate N-cycling microbial communities and in turn the nitrogen cycle. Here, we propose to study the effect viruses have on the virocell metabolism of nitrifying microorganisms, in particular ammonia oxidizing archaea (AOA) and bacteria (AOB). We hypothesize that viruses affect the rate and resilience of nitrification differently depending on their infection strategy and the interconnected dominating ammonia oxidizing population.