Comammox Nitrospira play an active role in nitrification of agricultural soils amended with nitrogen fertilizers

Abstract

The recent discovery of complete ammonia oxidizers (comammox Nitrospira) challenged the paradigm of the two-step nitrification mediated by two distinct groups of nitrifiers, and raised fundamental questions regarding their niche specialization and relative contribution to nitrification in agricultural soils. Previous studies suggest that comammox Nitrospira have an oligotrophic lifestyle and would outcompete canonical ammonia oxidizers (ammonia-oxidizing bacteria and ammonia-oxidizing archaea) under ammonia-limited conditions. Here, we demonstrated that comammox Nitrospira clade A were significantly more abundant than canonical ammonia oxidizers and 13CO2-DNA-stable isotope probing revealed ..