3, 4-Dimethylpyrazole phosphate is an effective and specific inhibitor of soil ammonia-oxidizing bacteria

A microcosm study was established using three arable soils differing in both physicochemical properties and AOB or AOA dominance of ammonia oxidization. Nitrification and N 2 O emissions were quantified under 10 Pa C 2 H 2 , 1-octyne, or 3,4-dimethylpyrazole phosphate (DMPP), and the community composition and abundance of AOA and AOB were assessed. Amendment of soil with DMPP had a comparable effect to 1-octyne on AOB activities, composition, and N 2 O emissions across soils. By blocking AOB activity, both DMPP and 1-octyne supported higher rates of AOA growth in both the acid and alkaline soils. Approximately, 50% of ammonia-oxidizing activity in the acid soil was attributed to AOB activity by phylotypes affiliated with Nitrosomonas communis . When AOB were blocked by DMPP or 1-octyne across all soils, recovery of AOA communities was associated with the increased abundance of Nitrososphaera viennesis .