The complete degradation of 1,2-dichloroethane in Escherichia coli by metabolic engineering

1,2-Dichloroethane (1,2-DCA), a widely utilized chemical intermediate and organic solvent in industry, frequently enters the environment due to accidental leaks and mishandling during application processes. Thus, the in-situ remediation of contaminated sites has become increasingly urgent. However, traditional remediation methods are inefficient and costly, while bioremediation presents a green, efficient, and non-secondary polluting alternative. In this study, an engineered strain capable of completely degrading 1,2-DCA was constructed. We introduced six exogenous genes of the 1,2-DCA degradation pathway into E. coli and confirmed their normal transcription and efficient expression in this engineered strain through qRT-PCR and proteomics. The degradation experiments showed that the strain completely degraded 2 mM 1,2-DCA within 12 h. Furthermore, the results of isotope tracing verified that the final degradation product, malic acid, entered the tricarboxylic acid cycle (TCA) of E. coli and was ultimately fully metabolized. Also, morphological changes in the engineered strain and control strain exposed to 1,2-DCA were observed under SEM, and the results revealed that the engineered strain is more tolerant to 1,2-DCA than the control strain. In conclusion, this study paved a new way for humanity to deal with the increasingly complex environmental challenges.