TY - JOUR
T1 - Expression of tfdA genes in aquatic microbial communities during acclimation to 2,4-dichlorophenoxyacetic acid
AU - de Lipthay, Julia R.
AU - Aamand, Jens
AU - Barkay, Tamar
N1 - Funding Information:
Jarek Letowski, Ruth Dorn and Jeffra Schaefer are acknowledged for valuable discussions and technical suggestions. We thank Jerry Kukor for plasmid pGEM-3Z, and Kaare Johnsen for critically reading the manuscript. This work was supported by the Danish Environmental Research Program, Pesticides and Groundwater.
PY - 2002/6
Y1 - 2002/6
N2 - The role of gene expression during acclimation of aquatic microbial communities was examined by relating transcription of tfdA to the degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The tfdA gene encodes for a 2,4-D/2-oxoglutarate dioxygenase that transforms 2,4-D to 2,4-dichlorophenol. Transcription of tfdA, the abundance of tfdA genes and 2,4-D degrading populations, and the rate of 2,4-D disappearance were followed in laboratory incubations of two pond water samples that were exposed to 0.11 mM 2,4-D. Both communities responded to 2,4-D exposure by induction of tfdA transcription but the dynamics of transcript abundance and the homology to the tfdA riboprobe suggested different populations of 2,4-D degraders in the two ponds. In one community, where tfdA transcripts were highly homologous to the tfdA gene of Ralstonia eutropha JMP134, transcription of tfdA was transient and dropped while 2,4-D degradation continued. In the other freshwater community, where tfdA genes with a lower similarity to the tfdA gene of strain JMP134 were transcribed, transcript levels remained high although 2,4-D degradation had ceased. Restriction fragment length polymorphism analysis of tfdA amplicons similarly demonstrated the presence of different tfdA loci in the two freshwater communities, and this difference in populations of tfdA genes probably explains the observed difference in dynamics of catabolic gene transcription.
AB - The role of gene expression during acclimation of aquatic microbial communities was examined by relating transcription of tfdA to the degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The tfdA gene encodes for a 2,4-D/2-oxoglutarate dioxygenase that transforms 2,4-D to 2,4-dichlorophenol. Transcription of tfdA, the abundance of tfdA genes and 2,4-D degrading populations, and the rate of 2,4-D disappearance were followed in laboratory incubations of two pond water samples that were exposed to 0.11 mM 2,4-D. Both communities responded to 2,4-D exposure by induction of tfdA transcription but the dynamics of transcript abundance and the homology to the tfdA riboprobe suggested different populations of 2,4-D degraders in the two ponds. In one community, where tfdA transcripts were highly homologous to the tfdA gene of Ralstonia eutropha JMP134, transcription of tfdA was transient and dropped while 2,4-D degradation continued. In the other freshwater community, where tfdA genes with a lower similarity to the tfdA gene of strain JMP134 were transcribed, transcript levels remained high although 2,4-D degradation had ceased. Restriction fragment length polymorphism analysis of tfdA amplicons similarly demonstrated the presence of different tfdA loci in the two freshwater communities, and this difference in populations of tfdA genes probably explains the observed difference in dynamics of catabolic gene transcription.
KW - 2,4-Dichlorophenoxyacetic acid
KW - Acclimation
KW - Catabolic gene transcription
KW - mRNA
KW - tfdA
UR - http://www.scopus.com/inward/record.url?scp=0036269478&partnerID=8YFLogxK
U2 - 10.1111/j.1574-6941.2002.tb00953.x
DO - 10.1111/j.1574-6941.2002.tb00953.x
M3 - Article
VL - 40
SP - 205
EP - 214
JO - FEMS Microbiology Ecology
JF - FEMS Microbiology Ecology
SN - 0168-6496
IS - 3
ER -