Wastewater-Derived Dissolved Organic Matter Composition Mediates Biodegradation of 17β-Estradiol-3-Sulfate by Shaping Assembly Mechanisms of Microbial Taxa

Dissolved organic matter (DOM) in natural waters influences the degradation of micropollutants (MPs) by regulating microbial communities. However, whether this pathway exists in wastewater treatment plants (WWTPs) and the underlying microbial mechanisms remain unclear. In this study, we investigated the relationships among DOM composition, microbial communities, and 17β-estradiol-3-sulfate (E2-3S) degradation across 12 WWTPs, and further elucidated how wastewater-derived DOM affects E2-3S degradation via microbial taxon assembly under controlled conditions. Results indicated significant network interactions among DOM components, microbial communities, and E2-3S degradation in the investigated WWTPs. Microbes showed distinct preferences for initial DOM during E2-3S degradation, resulting in differences in DOM removal and generation across groups. Core taxa dominated by homogeneous selection (HoS) were mainly responsible for bulk DOM removal, whereas rare taxa (ART) shaped by HoS (53.5%), heterogeneous selection (19.4%), and diffusion limitation (10.8%) were more favored to utilize newly generated DOM and participate in E2-3S degradation. Network analysis and structural equation modeling showed core taxa positively affected ART (p < 0.001), while ART, which are at an ecological disadvantage in DOM resource competition, exerted a significant positive influence on E2-3S removal (p < 0.001). These findings suggest that wastewater-derived DOM could affect the degradation process of MPs by modulating functional differentiation and cooperation among microbial taxa.