Identification of a virulent phage infecting species of Nitrosomonas

In the first and limiting step of nitrification, ammonia (NH₃) is oxidised to nitrite (NO₂^-) by the action of some prokaryotes, including bacteria of the Nitrosomonas genus. A potential approach to nitrification inhibition would be through the application of phages, but until now this method has been unexplored and no virulent phages that infect nitrifying bacteria have been described. In this study, we report the isolation of the first phage infecting some Nitrosomonas species. This polyvalent virulent phage (named ΦNF-1) infected Nitrosomonas europaea, Nitrosomonas communis, and Nitrosomonas nitrosa. Phage ΦNF-1 has the morphology of the Podoviridae family, a dsDNA genome of 41,596 bp and a 45.1 % GC content, with 50 predicted open reading frames. Phage ΦNF-1 was found to inhibit bacterial growth and reduce NH₄⁺ consumption in the phage-treated cultures. The application of phages as biocontrol agents could be a useful strategy for nitrification inhibition without the restrictions associated with chemical inhibitors.