Long-term response of microalgal-bacterial granular sludge to high-concentration sulfadiazine stress: Metagenomic and metatranscriptomic profiling

This project investigates the long-term adaptive response of microalgal-bacterial granular sludge (MBGS) systems to ultra-high concentrations of the antibiotic sulfadiazine (SDZ). The study compares two initial operational strategies, pre-acclimatization (with initial SDZ stress) and pre-accumulation (without initial stress), to assess their impact on system resilience, SDZ removal efficiency, microbial community succession, and the control of antibiotic resistance genes (ARGs).Over a 146-day semi-continuous operation, SDZ concentration was stepwise increased from 10 to 50 mg/L. Systems were monitored for pollutant removal, extracellular polymeric substance dynamics, oxidative stress response, and SDZ biodegradation pathways. Metagenomic sequencing was performed to analyze microbial community structure, functional genes (including cytochrome P450 enzymes), and ARG profiles.