Cometabolic degradation of dibenzofuran by Comamonas sp. MQ

• Strain MQ was used to degrade cometabolically DBF with other PAHs.
• LC/MS TOF was used to analysis the intermediates accurately.
• Two different metabolism pathways of DBF by strain MQ were proposed.

In this study, strain MQ belonging to the genera Comamonas was used to cometabolically degrade dibenzofuran (DBF) with naphthalene, phenanthrene, benzene, toluene, biphenyl and nitrobenzene, respectively, for the first time. Strain MQ could cometabolically degrade DBF in the growing system using naphthalene as a substrate and the Ki value of strain MQ on naphthalene and DBF was 90.26 mg L−1 and 68.34 mg L−1, respectively. The degradation rate of DBF by naphthalene-cultivated strain MQ cells (0.080 mmol L−1 h−1) was 1.05, 1.11, 1.13, 1.18 and 1.27-fold higher than that cultivated by phenanthrene, benzene, toluene, biphenyl and nitrobenzene, respectively. Examination of metabolites indicated that naphthalene-cultivated strain MQ cells degraded DBF to 2-hydroxy-4-(3′-oxo-3′H-benzofuran-2′-yliden)but-2-enoic acid (HOBB) and subsequently to salicylic acid via the lateral dioxygenation and meta cleavage pathway. In contrast, biphenyl-cultivated strain MQ cells degraded DBF to monohydroxydibenzofuran through the lateral dioxygenation without meta cleavage pathway. These results suggested that strain MQ could be useful in the bioremediation of environments contaminated by heterocyclic compounds mixtures with polycyclic aromatic hydrocarbons.