Abstract
Propiconazole is a widely used synthetic fungicide that has raised deep environmental and toxicological concerns due to its persistence and bioactivity. In this study, we investigated the potential of a facultative anaerobic, Gram-positive, rod-shaped bacterium, Bacillus paramycoides to degrade propiconazole by elucidating the functional role of its hydrolase enzyme in silico. The hydrolase was characterised with the FASTA sequence to determine its physicochemical properties, stability, and conserved functional domains. Homology modelling was performed and the predicted structure validated using a Ramachandran plot and ERRAT analysis, yielding an overall quality score of 93.6 %. Eleven propiconazole-related compounds, including parent molecules and degradation products (e.g. hispor, propiconazole TP1, propiconazole TP2, and propiconazole-d7) were retrieved from the PubChem database and subjected to molecular docking using PyRx. Docking analysis revealed stable enzyme-substrate interactions, with the highest binding affinity of -6.8 kcal/mol observed for native hydrolase complexes. Site-directed mutagenesis was subsequently performed, and mutant structures were evaluated for structural stability and functional integrity. The mutated hydrolase exhibited an improved binding affinity of -7.4 kcal/mol, indicating enhanced substrate interaction. Molecular dynamics simulations using the AMBER force field further confirmed the structural stability, binding consistency, and functional reliability of the enzyme-ligand complexes. Overall, these quantitative findings support the potential of B. paramycoides hydrolase as a stable, non-virulent, and efficient candidate for environmentally sustainable bioremediation of propiconazole, with relevance to environmental and occupational toxicology.