The Unique Roles of Microbial Abundant and Rare Taxa in Regulating Pathogen Dynamics in Wastewater Bioaerosols

Bioaerosols emitted from wastewater treatment plants (WWTPs) are key vectors for airborne microbial transmission, yet the mechanisms by which abundant and rare microbial taxa regulate pathogen dynamics remain unclear. This study explored the ecological roles of abundant and rare taxa through a comprehensive analysis of bioaerosols from two full-scale WWTPs, integrating high-throughput sequencing of bacterial and fungal communities. Results showed that the rare taxa exhibited higher alpha diversity, and their community construction was dominated by deterministic processes. While the abundant taxa showed higher spatial homogeneity, and their distribution was more consistent with the neutral model, suggesting the dominance of stochastic processes. Network analysis revealed that rare taxa held keystone topological roles within the microbial networks. Moreover, partial least squares path model quantified their direct effects on pathogen abundance, revealing a strong positive direct effect of abundant bacterial taxa but a significant negative direct effect of rare bacterial taxa. This study elucidates the dual roles of taxa with different abundance levels in community assembly and pathogen regulation, emphasizing that effective risk assessment and management strategies should account not only for the carrier role of abundant taxa but also for the regulatory function of the rare biosphere in shaping pathogen dynamics.