Deciphering key microbes and their interactions within anaerobic ammonia oxidation systems

[Display omitted] •The key microbes within the anammox system were identified.•Interaction relationships among key microbes in the anammox system were revealed.•Changes in interactions between key microbes under adverse conditions were analyzed.•Candidatus_Kuenenia is more adaptable and resilient to different environments.•Contribute to the development of more efficient anammox systems. The stability of anaerobic ammonium oxidation (anammox) performance is inseparably linked to the dynamic equilibrium of microbial interactions. However, understanding of the key microbes within anammox systems remains limited. Through the analysis of 186 16S rRNA datasets combined with various ecological analysis methods, this study identified key microbes in the anammox process. Interactions between Candidatus_Kuenenia and other key microbes are the most significant with greater tolerance to differing water quality, while Candidatus_Jettenia have higher habitat specificity. Under adverse conditions, anammox bacteria can reduce the impact of unfavorable environments by enhancing interactions with certain microbes. This study comprehensively reviews the main functions of key microbes in the anammox system and their interactions, and summarizes several common interaction mechanisms, providing new insights for understanding the startup and stable operation of the anammox process.