Micropollutant-driven bacterial adaptation enables resilient pharmaceuticals biodegradation at trace concentrations in biologically treated wastewater

Abstract

Pharmaceutical residues are persistent contaminants that resist conventional wastewater treatment and can disrupt ecosystems; however, microorganisms provide a promising biobased solution to transform or mineralize these complex xenobiotics. Whether pollutant-adapted communities maintain their degradative capacity under realistic environmental conditions remains a long-standing debate in environmental biotechnology. Here, microbial consortia enriched in six membrane bioreactors under high pharmaceutical concentration (100 mg/L) retained full biodegradation capacity across a 5000-fold concentration range. After prolonged exposure to six model compounds (atenolol, caffeine, diclofenac, enalapril, ibuprofen, and paracetamol) complete removal occurred for all except diclofenac. Degradation remained efficient even at lower and environmentally relevant concentrations (1 mg/L-20 µg/L) and recovered rapidly upon re-exposure to higher loads (100 mg/L). Metagenomic profiling revealed enrichment of oxygenase-mediated catabolic pathways supporting this resilience. When transferred to a 7 liters bioreactor treating real wastewater, the adapted community removed targeted and untargeted pharmaceuticals, demonstrating robustness, scalability, and strong potential for sustainable micropollutant remediation.