Nitrospira Raw sequence reads
As a newly discovered group of ammonia-oxidizing microorganisms, complete ammonia oxidizing (comammox) Nitrospira has been widely found in various oligotrophic ecosystems. However, their activity and ecological niche are still unclear in recirculating aquaculture systems (RAS). This study aimed to elucidate microbial community structure and metabolic versatility of active comammox Nitrospira, ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in RAS. Quantitative PCR (qPCR) results showed that either comammox Nitrospira or AOB numerically predominated, with comammox Nitrospira and AOA sharing similar low ammonia niches.