Biodegradation of erythromycin by Paracoccus kondratievae 6H01: efficiency, mechanistic insights, and bioremediation potential

The biodegradation of erythromycin has emerged as a cost-effective and eco-friendly strategy for mitigating antibiotic residues in contaminated ecosystems. This study reports the successful isolation of Paracoccus kondratievae 6H01, a novel erythromycin-degrading bacterium, through selective enrichment of antibiotic-contaminated soil microbiota. A comprehensive investigation of critical operational parameters revealed that the strain achieved 35.58% degradation efficiency against 320 mg/L erythromycin within 72 h under optimized conditions. Notably, comparative enzymatic analyses demonstrated the pivotal role of intracellular enzymes, which mediated 36.27% erythromycin depletion at equivalent concentrations. Liquid chromatography–mass spectrometry (LC–MS) profiling identified 9 principal degradation products, enabling the proposition of a multi-step metabolic pathway involving sequential dehydration, cleavage of cladinose, macrolide ring-opening, deglycosylation, and demethylation reactions. Finally, ecotoxicological assessments combining agar-diffusion assays and ECOSAR predictive modeling confirmed the significantly reduced toxicity of these biotransformation products compared to the parent compound. As the first comprehensive report elucidating both erythromycin catabolic machinery in Paracoccus kondratievae and associated detoxification mechanisms, this work advances the fundamental understanding of macrolide antibiotic bioremediation while providing a microbial resource for sustainable environmental biotechnology applications.