In vitro studies on reductive vinyl chloride dehalogenation by an anaerobic mixed culture

Abstract

Reductive dehalogenation of vinyl chloride (VC) was studied in an anaerobic mixed bacterial culture. In growth experiments, ethene formation from VC increased exponentially at a rate of about 0.019 h-1. Reductive VC dehalogenation was measured in vitro by using cell extracts of the mixed culture. The apparent K(m) for VC was determined to be about 76 μM; the V(max) was about 28 nmol · min-1 · mg of protein-1. The VC- dehalogenating activity was membrane associated. Propyl iodide had an inhibitory effect on the VC-dehalogenating activity in the in vitro assay. However, this inhibition could not be reversed by illumination. Cell extracts also catalyzed the reductive dehalogenation of cis-1,2-dichloroethene (cis- DCE) and, at a lower rate, of trichloroethene (TCE). Tetrachloroethene (PCE) was not transformed. The results indicate that the reductive dehalogenation of VC and cis-DCE described here is different from previously reported reductive dehalogenation of PCE and TCE.