Characterization of a Pure Culture of Dehalogenimonas Dechlorinating 4-Hydroxy-chlorothalonil and Its Putative Reductive Dehalogenase Gene by a Multiomics Approach

4-Hydroxy-chlorothalonil (4-OH-TPN), the main metabolite of the widely used fungicide chlorothalonil, has recently been reported to be reductively dechlorinated by an anaerobic consortium containing Dehalogenimonas . While the pure culture of the Dehalogenimonas has not been isolated and the reductive dehalogenase genes ( rdhAs ) responsible for the 4-OH-TPN dechlorination remain unclear. The assembled genome of Dehalogenimonas contained a 1,2-dichloroethane (1,2-DCA) reductive dehalogenase gene ( dcpA ) ortholog. In this study, by alternating the substrate from 4-OH-TPN to 1,2-DCA, a pure culture of Dehalogenimonas, designated as 4OHTPN1, was finally isolated. Strain 4OHTPN1 potentially represents a novel species in the genus Dehalogenimonas and contains 33 rdhA genes and 4 rdhB genes. The novel rdhA26 gene (designated htpnA ) was identified as the key gene involved in 4-OH-TPN dechlorination. Its transcriptional and protein expression levels were 25.0-fold and 10.2-fold higher than the average of all rdhA genes when the culture was solely amended with 4-OH-TPN. In contrast, the dcpA ortholog, rdhA25, exhibited 10.1-fold and 9.8-fold higher transcriptional and protein expression levels when only amended with 1,2-DCA, highlighting a substrate-specific regulatory response to a distinct electron acceptor. This study expands our knowledge of the rdhA gene for 4-OH-TPN dechlorination in the pure culture of Dehalogenimonas .