AUTHOR=Yang Xueqin , Yu Xiaoli , He Qiang , Deng Ting , Guan Xiaotong , Lian Yingli , Xu Kui , Shu Longfei , Wang Cheng , Yan Qingyun , Yang Yuchun , Wu Bo , He Zhili 

TITLE=Niche differentiation among comammox (Nitrospira inopinata) and other metabolically distinct nitrifiers

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.956860

DOI=10.3389/fmicb.2022.956860

ISSN=1664-302X

ABSTRACT=<p>Due to global change, increasing nutrient input to ecosystems dramatically affects the nitrogen cycle, especially the nitrification process. Nitrifiers including ammonia-oxidizing archaea (AOAs), ammonia-oxidizing bacteria (AOBs), nitrite-oxidizing bacteria (NOBs), and recently discovered complete ammonia oxidizers (comammoxs) perform nitrification individually or in a community. However, much remains to be learned about their niche differentiation, coexistence, and interactions among those metabolically distinct nitrifiers. Here, we used synthetic microbial ecology approaches to construct synthetic nitrifying communities (SNCs) with different combinations of <italic>Nitrospira inopinata</italic> as comammox, <italic>Nitrososphaera gargensis</italic> as AOA, <italic>Nitrosomonas communis</italic> as AOB, and <italic>Nitrospira moscoviensis</italic> as NOB. Our results showed that niche differentiation and potential interactions among those metabolically distinct nitrifiers were determined by their kinetic characteristics. The dominant species shifted from <italic>N. inopinata</italic> to <italic>N. communis</italic> in the N4 community (with all four types of nitrifiers) as ammonium concentrations increased, which could be well explained by the kinetic difference in ammonia affinity, specific growth rate, and substrate tolerance of nitrifiers in the SNCs. In addition, a conceptual model was developed to infer niche differentiation and possible interactions among the four types of nitrifiers. This study advances our understanding of niche differentiation and provides new strategies to further study their interactions among the four types of nitrifiers.</p>