Prediction of Dechlorination Pathways of Diverse Chlorinated Aromatic Pollutants Conducted by Dehalococcoides ethenogenes Strain 195

Abstract

Dechlorination of chlorinated aromatic pollutants (CAPs) has become a major issue in recent decades. This paper reported a theoretical indicator for proposing the reductive dechlorination pathways of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and chlorobenzenes transformed by Dehalococcoides ethenogenes strain 195. Quantum chemical calculations were carried out at the HF/6-31G(d) level for all related chlorinated aromatic pollutants and molecular total energy (E_T) of structuraly possible daughter products was adopted as the probe of the dechlorination reaction activity. E_T could indicate the main dechlorination daughter products of PCDD/Fs, PCBs and chlorobenzenes conducted by strain 195. The dechlorination reaction favoured the formation of daughter product having the lowest E_T. In addition, the energy gap (DE_T) between a structurally possible daughter product and the possible daughter product having the lowest E_T could be used to estimate the existence of multiple daughter products: the smaller the DE_T, the more possible to form multiple daughter products.