Summary: APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Nov. 2005, p. 71457151 Vol. 71, No. 11
0099-2240/05/$08.00 0 doi:10.1128/AEM.71.11.71457151.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Transcriptional Expression of the tceA Gene in a
David R. Johnson, Patrick K. H. Lee, Victor F. Holmes,
Alexander C. Fortin, and Lisa Alvarez-Cohen*
Department of Civil and Environmental Engineering,
University of California, Berkeley, California
Received 4 May 2005/Accepted 20 July 2005
Dynamic changes in the transcriptional expression of the tceA gene, which encodes a trichloroethene
reductive dehalogenase, were characterized in a Dehalococcoides-containing microbial enrichment culture.
Expression was quantified by real-time PCR as the number of tceA transcripts per tceA gene. Expression of tceA
increased 40-fold after chlorinated ethene-starved cells were exposed to trichloroethene (TCE), cis-dichlo-
roethene (DCE), or 1,1-DCE but did not increase after exposure to tetrachloroethene or vinyl chloride.
Surprisingly, tceA expression also increased 30-fold after cellular exposure to the nonmetabolic substrate
trans-DCE, indicating that expression of tceA is induced by both growth-supporting and non-growth-supporting
chlorinated ethenes. Additional experiments revealed that the level of tceA expression was independent of the
concentration of chlorinated ethenes (sum concentrations of TCE and DCEs of 2.2 to 333 M), the concen-