Comparative studies on tetrachloroethene reductive dechlorination mediated by Desulfitobacterium sp. strain PCE-S
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© Springer-Verlag 1997
O R I G I N A L PA P E R
Evelyn Miller · Gert Wohlfarth · Gabriele Diekert
Comparative studies on tetrachloroethene reductive dechlorination mediated by Desulfitobacterium sp. strain PCE-S
Received: 28 April 1997 / Accepted: 11 July 1997
Abstract Tetrachloroethene reductive dechlorination was studied with cell extracts of a newly isolated, tetrachloroethene-utilizing bacterium, Desulfitobacterium sp. strain PCE-S. Tetrachloroethene dehalogenase mediated the reductive dechlorination of tetrachloroethene and trichloroethene to cis-1,2-dichloroethene with artificial electron donors such as methyl viologen. The chlorinated aromatic compounds tested so far were not reduced. A low-potential electron donor (E0′ < –0.4 V) was required for tetrachloroethene reduction. The enzyme in its reduced state was inactivated by propyl iodide and reactivated by light, indicating the involvement of a corrinoid in reductive tetrachloroethene dechlorination. Key words Corrinoids · Dehalospirillum multivorans · Desulfitobacterium · Tetrachloroethene dehalogenase · Propyl iodide · Reductive dechlorination · Strain PCE-S · Tetrachloroethene · Trichloroethene
Introduction Members of the genus Desulfitobacterium and the related “Dehalobacter restrictus” are gram-positive bacteria that are able to reductively dehalogenate a variety of chlorinated hydrocarbons including chlorinated phenols and/or alkenes in their energy metabolism. Tetrachloroethene reductive dechlorination in pure cultures has been described so far only for the gram-negative bacteria Dehalospirillum multivorans (Neumann et al. 1994; Scholz-Muramatsu et al. 1995), Desulfomonile tiedjei (Fathepure et al. 1987), strain MS-1 (Sharma and McCarty 1996), and strain TT4B (Krumholz et al. 1996) and for the gram-positive bacteria “Dehalobacter restrictus” (Holliger and Schumacher 1994) and Desulfitobacterium strain PCE1 (Gerritse et al. 1996).
E. Miller · G. Wohlfarth · G. Diekert (Y) Institut für Mikrobiologie, Universität Stuttgart, Allmandring 31, D-70569 Stuttgart, Germany Tel. +49-711-6855483; Fax +49-711-6855725 e-mail: [email protected]
For a recent review on microbial reductive dehalogenation, the reader is referred to Wohlfarth and Diekert (1997). Tetrachloroethene dechlorination has been investigated in cell-free systems in Dehalospirillum multivorans (Neumann et al. 1995, 1996), “Dehalobacter restrictus” (Schumacher and Holliger 1996), and Desulfomonile tiedjei (Townsend and Suflita 1996). Tetrachloroethene reductive dehalogenase has been purified from the cytoplasmic fraction of Dehalospirillum multivorans cells (Neumann et al. 1996). It was shown to contain a corrinoid as well as Fe and acid-labile sulfur. Vitamin B12 is involved in this reaction presumably as a redox-active prosthetic group, as is deduced from the finding that it has to be reduced to cob(I)alamin prior to the nucleophilic attack on the carbon of tetrachloroethene (Wohlfarth and Diekert 1997). Since the redox-active group of tetrachloroethene dehalogenase has a low stand
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