Temperature phase shift determines microbial community succession and assembly pattern in climate-stressed wastewater...

Seasonal temperature changes exert periodic disturbances on microbial communities in wastewater treatment plants (WWTPs), yet mechanisms governing their seasonal assembly remain unclear. Tracking a full-scale WWTP over a year, this study shows that temperature variation processes, rather than temperature extremes, are the primary driver of microbial community succession and deterministic assembly. Microbial community structure and co-occurrence networks varied across temperature phases, with network complexity declining during temperature-shift phases (either warming or cooling phases) but stabilizing at temperature-stable phases (either hot or cold phases). Deterministic selection surged to 25.5% exclusively during the warming phase, identifying warming process as the key factor for microbial community restructuring. The temperature phase shifts trigger distinct response patterns of microbial communities to other environmental factors. This work emphasizes temperature dynamics as a critical ecological filter and provides a temperature-phase-specific insight for optimizing WWTP management under seasonal stress.