Anthracene degradation involved by antibiotic biosynthesis monooxygenase (ABM) in Comamonas testosteroni

It is well known that anthracene can cause serious health problems, which is why anthracene biodegradation as a method to reduce health risks has drawn the interest of researchers. However, antibiotic contamination in the environment can seriously affect the biodegradation of anthracene. In the present study, Comamonas testosteroni (CT1) had the highest degradation efficiency of anthracene (88.1%), and was still 46.6% when erythromycin concentration was 1/4MIC (8 μg mL⁻¹). Also, compared to CK, the prokaryotic transcriptome analysis of CT1 in anthracene degradation revealed an up-regulated gene that encodes antibiotic biosynthesis monooxygenase (ABM) in both anthracene and anthracene-erythromycin groups. In addition, compared to strain CT1, the CtABM knockout mutant (CT-M) showed a significant decrease in anthracene degradation efficiency. In contrast, Escherichia coli (E.coli) DH5α transformed with CtABM (EM1) exhibited a faster degradation efficiency than DH5α. Furthermore, the antimicrobial susceptibility test showed that compared to DH5α, EM1 had significant resistance to erythromycin. And the purified recombinant CtABM (rABM) had a specific activity of 2.53 μmol min⁻¹·mg⁻¹ protein based on the oxidation of anthracene at pH 7.5 and 35 °C. Additionally, compositional analysis identified 4-benzyloxy-3-methoxybenzyl alcohol and 4-methylphthalaldehyde as anthracene metabolites by EM1, suggesting a novel anthracene degradation pathway.