In vivo regulation of organohalide respiration in Desulfitobacterium hafniense DCB-2

Background Organohalide respiration (OHR) is a bacterial anaerobic respiratory metabolism which takes advantage of halogenated compounds (= organohalides) as terminal electron acceptors. While its environmental interest does not have to be demonstrated anymore, many aspects of this process remain poorly characterized. We have decided to explore the regulatory network of OHR in Desulfitobacterium hafniense strain DCB-2, a typical OHR bacterium showing a versatile energy metabolism which harbours seven distinct reductive dehalogenase (rdh) gene clusters potentially involved in OHR. Methods Strain DCB-2 was cultivated anaerobically with lactate and fumarate (under respiration conditions) or with pyruvate (under fermentation conditions) and exposed to various chlorinated phenol derivatives, after which RNA was extracted from samples collected at different time intervals. A combination of reverse transcription, qPCR and transcriptomic analysis targeting genes belonging to rdh gene clusters will allow a quantitative analysis of the activity of selected RdhK proteins which are involved in transcriptional regulation. Results This study aims at deciphering the role and cross-talk of characterized and uncharacterized RdhK regulatory proteins of strain DCB-2 in vivo. The activation of transcription of rdh gene clusters after addition of selected chlorophenols will be presented and discussed. Conclusions These data will be confronted to results obtained from in vitro experiments describing the tripartite interaction of purified RdhK proteins with the chlorophenols and the targeted DNA promoters (see also the abstract by M. Willemin et al.).