Niche specialization of comammox <i>Nitrospira</i> in terrestrial ecosystems: Oligotrophic or copiotrophic?

The discovery of complete ammonia oxidizers, comammox Nitrospira, represents a breakthrough in the history nitrification research. Nitrospira inopinata, which was obtained from an aquatic ecosystem, is only pure bacterial isolate reported so far. Ammonia oxidation kinetics N. inopinata indicated that they prefer oligotrophic lifestyle and may directly compete with ammonia-oxidizing archaea (AOA), but representatives terrestrial ecosystems are lacking. Current studies demonstrate functionally dominant separated most sequences engineering systems. Clades A B seemingly have different ecological preferences soils, possibly due to their ammonium uptake Analyses evolutionary indicate some genes involved could be laterally transferred β-ammonia-oxidizing bacteria (AOB). Some species similar AOB active niches where previously considered dominated by AOB. Taken together, this review summarizes recent findings biogeographical distribution preference large-scale soil surveys, responses nitrogen application soil, putative mechanisms underpinning niche Nitrospira. These suggest not strictly both copiotrophic broader breadth. Comammox abundant environments. profoundly expanded our knowledge environmental relative contribution soils.