Dehalogenimonas lykanthroporepellens BL ‐ DC ‐9 T simultaneously transcribes many rdhA genes during organohalide respiration with 1,2‐ DCA , 1,2‐ DCP , and 1,2,3‐ TCP as electron acceptors

The genome sequence of the organohalide‐respiring bacterium Dehalogenimonas lykanthroporepellens BL ‐ DC ‐9 T contains numerous loci annotated as reductive dehalogenase homologous ( rdh ) genes based on inferred protein sequence identity with functional dehalogenases of other bacterial species. Many of these genes are truncated, lack adjacent regulatory elements, or lack cognate genes coding for membrane‐anchoring proteins typical of the functionally characterized active reductive dehalogenases of organohalide‐respiring bacteria. To investigate the expression patterns of the rdh genes in D. lykanthroporepellens BL ‐ DC ‐9 T , oligonucleotide primers were designed to uniquely target 25 rdh genes present in the genome as well as four putative regulatory genes. RNA extracts from cultures of strain BL ‐ DC ‐9 T actively dechlorinating three different electron acceptors, 1,2‐dichloroethane, 1,2‐dichloropropane, and 1,2,3‐trichloropropane were reverse‐transcribed and subjected to PCR amplification using rdh‐ specific primers. Nineteen rdh gene transcripts, including 13 full‐length rdhA genes, six truncated rdhA genes, and five rdhA genes having cognate rdhB genes were consistently detected during the dechlorination of all three of the polychlorinated alkanes tested. Transcripts from all four of the putative regulatory genes were also consistently detected. Results reported here expand the diversity of bacteria known to simultaneously transcribe multiple rdh genes and provide insights into the transcription factors associated with rdh gene expression.