Harnessing the Infectivity and Stability of Bacteriophage ΦNF-1 in a Phage-Based Product for Sustainable...

The intensive use of nitrogen fertilizers sustains crop productivity but causes substantial nitrogen losses, greenhouse gas emissions, and water contamination through nitrification-driven leaching and volatilization. Although chemical nitrification inhibitors reduce these effects, concerns over persistence, toxicity, and impacts on nontarget organisms limit their sustainability. As a biological alternative, bacteriophages can selectively suppress ammonia-oxidizing bacteria (AOB) responsible for nitrification. This study examines the virulent bacteriophage ΦNF-1, the first known phage infecting soil AOB of the genus Nitrosomonas. ΦNF-1 reduced nitrification in fertilized soils inoculated with Nitrosomonas europaea and, to a lesser extent, in fertilized soils containing native AOB communities. Beyond its previously reported hosts, ΦNF-1 also propagated in Nitrosomonas oligotropha and Nitrosospira multiformis, expanding its known host range. ΦNF-1 remained infectious for over six months in aqueous suspensions at 4-20 °C and neutral to alkaline pH, but declined rapidly under acidic conditions. In agricultural soils, infectivity persisted for up to six months, though recovery was lower in sandy soils. A calcium carbonate-based photoprotectant significantly enhanced phage survival under UV and sunlight exposure. Overall, ΦNF-1 shows strong potential as a stable, host-specific biological nitrification inhibitor to improve nitrogen use efficiency and reduce environmental impacts of fertilization.