<i>Dehalogenimonas</i> Strain W from Estuarine\nSediments Dechlorinates 1,2-Dichloroethane under Elevated Salinity

Organohalide-respiring bacteria (OHRB) have been found\nin various\nenvironments and play an indispensable role in the biogeochemical\ncycling and detoxification of halogenated organic compounds (HOCs).\nCurrently, few ORHB have been reported to perform reductive dechlorination\nunder high salinity conditions, indicating a knowledge gap on the\ndiversity of OHRB and the survival strategy of OHRB in saline environments\n(e.g., estuarine, marine). This study reports the characterization\nof an enrichment culture dominated by a new Dehalogenimonas population strain W derived from estuarine sediments, which demonstrates\nthe capability to dechlorinate 1,2-dichloroethane (1,2-DCA) to ethene\nunder elevated salinity (≥5.1% NaCl, w/v). Metagenomic and\nproteomic analyses revealed that the distinctive high-salinity dechlorination\nof strain W is primarily attributed to a putative reductive dehalogenase\n(RDase) DdeA, which shares >91.4% amino acid identity with the\ndihaloeliminating\nRDase DcpA from other Dehalogenimonas strains. Additionally, ectoine biosynthesis enzymes (EctABC) contribute\nto the strain’s salt tolerance. These findings underscore the\npotential of OHRB, particularly Dehalogenimonas, to detoxify HOCs in high-salinity environments, such as estuarine\nand marine ecosystems, by employing compatible solutes as an adaptive\nmechanism.