Phenol-driven cometabolic degradation of cis-1,2-dichloroethene (cDCE): insights from Acinetobacter pittii and Ectopseudomonas alcaliphila

Abstract Accumulation of xenobiotic chlorinated ethenes (CEs) at legacy industrial soil and groundwater sites around the world is a pressing environmental and public health issue. Understanding the biochemical pathways through which microorganisms degrade c DCE is key to developing cost-effective, sustainable bioremediation strategies for CE contamination. Two strains, Acinetobacter pittii CEP14 and Ectopseudomonas alcaliphila JAB1, isolated from contaminated industrial sites, have demonstrated the ability to cometabolically degrade c DCE in the presence of phenol. In this study, we integrate transcriptomics, using differential gene expression analysis to pinpoint genes induced during c DCE co‐metabolism, with proteomics to confirm protein‐level expression. We use heterologous expression experiments to demonstrate that phenol monooxygenase is responsible for oxidising c DCE in both strains. Furthermore, we show that CEP14 and JAB1 α-subunits share 71.4% identity with each other but only 14.6–26.5% identity with established monooxygenases with known c DCE-oxidising activity, highlighting the diversity of enzymes that may be capable of cometabolic c DCE degradation. Finally, we hypothesise on a two-branch phenol monooxygenase-mediated c DCE degradation pathway in which the chemical degradative intermediates 2,2-dichloroacetaldehyde and c DCE epoxides are formed. This study sheds light on the biochemical mechanisms by which monoaromatic compounds can enhance the biodegradation of c DCE and demonstrates the potential utilisation of strains CEP14 and JAB1 for the biodegradation of c DCE.