Selective Enrichment of Comammox Nitrospira in a Moving Bed Biofilm Reactor with Sufficient Oxygen Supply

• DOI: 10.1021/acs.est.2c03299
• Publication Date: 2022-09-01T14:15:32Z
• Authors: Jing Zhao; Min Zheng; Zicheng Su; Tao Liu; Jie Li; Jianhua Guo; Zhiguo Yuan; Shihu Hu
• Keywords: Nitrospira

The recent discovery of comammox (complete ammonia oxidation) Nitrospira has upended the long-held nitrification paradigm. Although have been identified in wastewater treatment systems, conditions for their dominance over canonical oxidizers remain unclear. Here, we report a moving bed biofilm reactor (MBBR) fed with synthetic mainstream wastewater. Integrated 16S rRNA gene amplicon sequencing, fluorescence situ hybridization (FISH), and metagenomic sequencing methods demonstrated selective enrichment bacteria when MBBR was operated at dissolved oxygen (DO) concentration above 6 mg O2/L. (i.e., Nitrosomonas) attributed to low residual ammonium (0.02–0.52 N/L) formed high-DO MBBR. Two clade A were identified, which are phylogenetically close Candidatus nitrosa. Interestingly, cryosectioning-FISH showed these two species spatially distributed on surface biofilm. Moreover, ammonia-oxidizing activity Nitrospira-dominated biofilms susceptible supply, dropped by half DO decrease from 2 These features collectively suggest apparent affinity nitrifying