Canonical ammonia oxidizers, rather than comammox Nitrospira, dominated autotrophic nitrification during the mineralization of organic substances in two paddy soils

Abstract

Chemoautotrophic canonical ammonia-oxidizers and complete ammonia oxidizers (comammox) are responsible for ammonia oxidation, which is the rate-limiting step of nitrification in terrestrial ecosystems. However, the relative importance of autotrophic nitrification and the related active nitrifiers during mineralization of organic substances with different C/N ratios have not been fully elucidated to date. In this study, 15N tracing and 13CO2-DNA-based stable isotope probing (DNA-SIP) techniques were employed to investigate the responses of soil nitrification processes and the active nitrifying phylotypes in acidic and neutral paddy soils with amendment of glutamine (Gln) or rice straw with lo..