Dehalococcoides mccartyi Strain JNA in Pure Culture Extensively Dechlorinates Aroclor 1260 According to Polychlorinated Biphenyl (PCB) Dechlorination Process N

Abstract

We isolated Dehalococcoides mccartyi strain JNA from the JN mixed culture which was enriched and maintained using the highly chlorinated commercial PCB mixture Aroclor 1260 for organohalide respiration. For isolation we grew the culture in minimal liquid medium with 2,2',3,3',6,6'-hexachlorobiphenyl (236-236-CB)(20 μM) as respiratory electron acceptor. We repeatedly carried out serial dilutions to extinction and recovered dechlorination activity from transfers of 10(-7) and 10(-8) dilutions. Fluorescence microscopy, DGGE and RFLP analysis of PCR amplified16S rRNA genes, and multilocus sequence typing of three housekeeping genes confirmed culture purity. No growth occurred on complex media. JNA dechlorinated most hexa- and heptachlorobiphenyls in Aroclor 1260 (50 μg/mL) leading to losses of 51% and 20%, respectively. Dechlorination was predominantly from flanked meta positions of 34-, 234-, 235-, 236-, 245-, 2345-, 2346-, and 2356-chlorophenyl rings, as indicated by the underscores. The major products were 24-24-CB, 24-26-CB, 24-25-CB, and 25-26-CB. We identified 85 distinct PCB dechlorination reactions and 56 different PCB dechlorination pathways catalyzed by JNA. Dechlorination pathways were confirmed by mass balance of substrates and products. This dechlorination pattern matches PCB Dechlorination Process N. JNA is the first pure culture demonstrated to carry out this extensive and environmentally relevant PCB dechlorination pattern.

Thermal dechlorination of PCB-209 over Ca species-doped Fe2O3

“…The dechlorination pattern in our study was similar with that of PCB dechlorination over iron-based spinel at 300°C (Huang et al, 2013) and microbial reductive dechlorination of PCBs in soils and aquatic sediments under anaerobic conditions (Wiegel and Wu, 2000). The dechlorination pattern described above matches PCB dechlorination Process N, which defined microbiologically mediated dechlorination of PCBs which typically removes meta and/or para chlorines to generate primarily ortho-substituted lower chlorinated biphenyls (Wiegel and Wu, 2000;LaRoe et al, 2014).…”

PCB dechlorinases revealed at last

“…It turns out that three other D. mccartyi strains, 195 (12), GT (13), and JNA (11), each have an RDase that is also nearly identical to PcbA4 and PcbA5. Strains 195 and JNA also have the ability to dechlorinate Aroclor 1260 (11,14). Are these as yet uncharacterized RDases in fact PCB RDases?…”

“…First, that each enzyme can catalyze the dechlorination of dozens of PCB congeners as well as PCE (1). It was previously established that single pure strains of D. mccartyi could replicate complex patterns of Aroclor 1260 dechlorination that occur in the environment (10,11). However, it was not known whether this dechlorination resulted from a single RDase enzyme or from multiple RDases.…”

Ecophysiology and environmental distribution of organohalide-respiring bacteria

“…Recently, more strains from this species were isolated including strain JNA [85,86], CG1 [87,88], CG4 [87,88], CG5 [87,88], SG1 [87,88], AD14-1 [89] and AD14-2 [89].…”

“…Dehalococcoides mccartyi JNA Housatonic River sediment with Aroclor 1260-contamination 2014 [85,86] Dehalococcoides mccartyi VS Aquifer material from a PCE-contaminated site 2004 [101,163] Dehalococcoides mccartyi 195…”