Applied and Environmental Microbiology, December 1999, p. 5212-5221, Vol. 65, No. 12
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
TNO Institute of Environmental Sciences, Energy Research and Process Innovation, Department of Environmental Biotechnology, 7300 AH Apeldoorn,1 and Department of Microbiology, University of Groningen, 9751 NN Haren,2 The Netherlands, and Department of Food Science and Technology, University of Reading, Reading RG6 6AP, United Kingdom3
Received 21 May 1999/Accepted 8 September 1999
Strain TCE1, a strictly anaerobic bacterium that can grow by
reductive dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE), was isolated by selective enrichment from a PCE-dechlorinating chemostat mixed culture. Strain TCE1 is a gram-positive, motile, curved
rod-shaped organism that is 2 to 4 by 0.6 to 0.8 µm and has
approximately six lateral flagella. The pH and temperature optima for
growth are 7.2 and 35°C, respectively. On the basis of a comparative
16S rRNA sequence analysis, this bacterium was identified as a new
strain of Desulfitobacterium frappieri, because it
exhibited 99.7% relatedness to the D. frappieri type
strain, strain PCP-1. Growth with H2, formate,
L-lactate, butyrate, crotonate, or ethanol as the electron
donor depends on the availability of an external electron acceptor.
Pyruvate and serine can also be used fermentatively. Electron donors
(except formate and H2) are oxidized to acetate and
CO2. When L-lactate is the growth substrate, strain TCE1 can use the following electron acceptors: PCE and TCE (to
produce cis-1,2-dichloroethene), sulfite and thiosulfate (to produce sulfide), nitrate (to produce nitrite), and fumarate (to
produce succinate). Strain TCE1 is not able to reductively dechlorinate
3-chloro-4-hydroxyphenylacetate. The growth yields of the newly
isolated bacterium when PCE is the electron acceptor are similar to
those obtained for other dehalorespiring anaerobes (e.g.,
Desulfitobacterium sp. strain PCE1 and
Desulfitobacterium hafniense) and the maximum specific
reductive dechlorination rates are 4 to 16 times higher (up to 1.4 µmol of chloride released · min
1 · mg of
protein
1). Dechlorination of PCE and TCE is an inducible
process. In PCE-limited chemostat cultures of strain TCE1,
dechlorination is strongly inhibited by sulfite but not by other
alternative electron acceptors, such as fumarate or nitrate.
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