Biodegradation of trimethoprim antibiotic by white rot fungus Trametes hirsuta D7 and its laccase: quantitative analysis, molecular docking, and metabolic pathway

Antibiotic contamination in water and the environment is a major concern because it can potentially increase the risk of antimicrobial resistance (AMR). Trimethoprim (TMP) is challenging to degrade due to its stable chemical structure and low water solubility. This study examined TMP degradation by the white-rot fungus Trametes hirsuta D7 and its laccase enzyme. Using whole fungal mycelia at room temperature for 7 days, the fungus degraded 55.89% of TMP, with a laccase activity of 0.31 U/mL. Crude laccase treatment achieved 77.72% TMP removal within 4 h, while the laccase-ABTS system achieved complete degradation. Antibacterial assays against pathogenic bacteria demonstrated that the metabolites formed exhibited reduced antibacterial activity, with decreases of 48.29% and 21.43% against Staphylococcus aureus and Escherichia coli, respectively. LC-HRMS analysis indicated the formation of 2,6-diaminopyrimidin-5-ol as a hydroxylated metabolite via degradation. Four transformation products (TPs) (TP307, TP151, TP169, and TP253) were also identified, suggesting demethylation, hydroxylation, benzyl oxidation, and aromatic ring cleavage of TMP. Molecular docking analysis revealed a binding energy of −5.809 kcal/mol for the interaction between laccase and the TMP complex. This study highlights a promising capability of T. hirsuta D7 and its laccase enzyme for efficient bioremediation of TMP in contaminated environments.