The significant contribution of comammox bacteria to nitrification in a constructed wetland revealed by DNA-based stable isotope probing

• Published in: Bioresource technology 2024-05, Vol.399, p.130637-130637, Article 130637
• Main Authors: Zhang, Anqi, Zhu, Mingyang, Zheng, Yize, Tian, Zhichao, Mu, Guangli, Zheng, Maosheng
• Format: Article
• Language: English
• Subjects: ammonia; Ammonia oxidation; Ammonia-oxidizing archaea; Ammonia-oxidizing bacteria; Archaea; Comammox bacteria; Constructed wetland; constructed wetlands; Nitrification; nitrogen cycle; oxidation; phylogeny; sediments; soil; stable isotopes; technology
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2024.130637

[Display omitted] •DNA-SIP was utilized to investigate the activity of three AOMs.•The sediment and shoreside zones were hotspots of nitrification in CWs.•Ntrospira nitrosa was the dominant active CMX species in CWs.•The role of CMX in ammonia oxidation in CWs cannot be overlooked. The discovery of Comammox bacteria (CMX) has changed our traditional concept towards nitrification, yet its role in constructed wetlands (CWs) remains unclear. This study investigated the contributions of CMX and two canonical ammonia-oxidizing microorganisms, ammonia-oxidizing bacteria (AOB) and archaea to nitrification in four regions (sediment, shoreside, adjacent soil, and water) of a typical CW using DNA-based stable isotope probing. The results revealed that CMX not only widely occurred in sediment and shoreside zones with high abundance (5.08 × 104 and 6.57 × 104 copies g−1 soil, respectively), but also actively participated in ammonia oxidation, achieving ammonia oxidation rates of 1.43 and 2.00 times that of AOB in sediment and shoreside, respectively. Phylogenetic analysis indicated that N. nitrosa was the dominant and active CMX species. These findings uncovered the crucial role of CMX in nitrification of sediment and shoreside, providing a new insight into nitrogen cycle of constructed wetlands.