title: Genomic characterization of three unique Dehalococcoides that respire on persistent polychlorinated biphenyls.
abstract: Fastidious anaerobic bacteria play critical roles in environmental bioremediation of halogenated compounds. However, their characterization and application have been largely impeded by difficulties in growing them in pure culture. Thus far, no pure culture has been reported to respire on the notorious polychlorinated biphenyls (PCBs), and functional genes responsible for PCB detoxification remain unknown due to the extremely slow growth of PCB-respiring bacteria. Here we report the successful isolation and characterization of three Dehalococcoides mccartyi strains that respire on commercial PCBs. Using high-throughput metagenomic analysis, combined with traditional culture techniques, tetrachloroethene (PCE) was identified as a feasible alternative to PCBs to isolate PCB-respiring Dehalococcoides from PCB-enriched cultures. With PCE as an alternative electron acceptor, the PCB-respiring Dehalococcoides were boosted to a higher cell density (1.2 × 10(8) to 1.3 × 10(8) cells per mL on PCE vs. 5.9 × 10(6) to 10.4 × 10(6) cells per mL on PCBs) with a shorter culturing time (30 d on PCE vs. 150 d on PCBs). The transcriptomic profiles illustrated that the distinct PCB dechlorination profile of each strain was predominantly mediated by a single, novel reductive dehalogenase (RDase) catalyzing chlorine removal from both PCBs and PCE. The transcription levels of PCB-RDase genes are 5-60 times higher than the genome-wide average. The cultivation of PCB-respiring Dehalococcoides in pure culture and the identification of PCB-RDase genes deepen our understanding of organohalide respiration of PCBs and shed light on in situ PCB bioremediation.
authors.affiliation: Departments of Civil and Environmental Engineering and.
authors.forename: Shanquan
authors.initials: S
authors.lastname: Wang
authors.affiliation: Departments of Civil and Environmental Engineering andComputational and Systems Biology, Genome Institute of Singapore, Singapore 138672.
authors.forename: Kern Rei
authors.initials: KR
authors.lastname: Chng
authors.affiliation: Computational and Systems Biology, Genome Institute of Singapore, Singapore 138672.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wilm
authors.affiliation: Departments of Civil and Environmental Engineering and.
authors.forename: Siyan
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576; and.
authors.forename: Kun-Lin
authors.initials: KL
authors.lastname: Yang
authors.affiliation: Computational and Systems Biology, Genome Institute of Singapore, Singapore 138672 nagarajann@gis.a-star.edu.sg jianzhong.he@nus.edu.sg.
authors.forename: Niranjan
authors.initials: N
authors.lastname: Nagarajan
authors.affiliation: Departments of Civil and Environmental Engineering and nagarajann@gis.a-star.edu.sg jianzhong.he@nus.edu.sg.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: He
mesh_terms: D041862:Chloroflexi / Q000235:genetics* / Q000378:metabolism; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D011078:Polychlorinated Biphenyls / Q000378:metabolism*; D016133:Polymerase Chain Reaction
chemical_list: D011078:Polychlorinated Biphenyls