|Global transcriptome analysis of the tetrachloroethene-dechlorinating bacterium
Desulfitobacterium hafniense Y51 in the presence of various electron donors and terminal electron acceptors.
J. Ind. Microbiol. Biotechnol. 39: 255-268. 2012.
X. Peng, S. Yamamoto, A.A. Vertes, G. Keresztes, K. Inatomi, M. Inui and H. Yukawa.
|Desulfitobacterium hafniense Y51 is a dechlorinating bacterium that encodes an unusually large set of O-demethylase paralogs and specialized respiratory systems including specialized
electron donors and acceptors. To use this organism in bioremediation of
tetrachloroethene (PCE) or trichloroethene (TCE) pollution, expression
patterns of its 5,060 genes were determined under different conditions
using 60-mer probes in DNA microarrays. PCE, TCE, fumarate, nitrate, and
dimethyl sulfoxide (DMSO) respiration all sustain the growth of strain
Y51. Global transcriptome analyses were thus performed using various electron
donor and acceptor couples (respectively, pyruvate and either fumarate,
TCE, nitrate, or DMSO, and vanillate/fumarate). When TCE is used as terminal
electron acceptor, resulting in its detoxification, a series of electron
carriers comprising a cytochrome bd-type quinol oxidase (DSY4055-4056), a ferredoxin (DSY1451), and four Fe-S
proteins (DSY1626, DSY1629, DSY0733, DSY3309) are upregulated, suggesting
that the products of these genes are involved in PCE oxidoreduction. Interestingly,
the PCE dehalogenase cluster (pceABCT) is constitutively expressed in the media tested, with pceT being upregulated and pceC downregulated in pyruvate/TCE-containing medium. In addition, another
dehalogenation enzyme (DSY1155 coding for a putative chlorophenol reductive
dehalogenase), is induced 225-fold in that medium, despite not being involved
in PCE respiration. Remarkably since the reducing equivalents formed during
pyruvate conversion to acetyl-CoA are channeled to electron acceptors including
halogenated compounds, pyruvate induces expression of a pyruvate:ferredoxin
oxidoreductase. This study paves the way to understanding the physiology
of D. hafniense, optimizing this microbe as a bioremediation agent, and designing bioarray sensors to monitor the presence of dechlorinating organisms in the environment.