PCB dechlorinases revealed at last

Bedard, Donna L.

doi:10.1073/pnas.1412286111

Cited by 12 publications

(11 citation statements)

References 16 publications

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“…RDases involved in PCB dechlorination have been elusive until recently when three PCB RDase genes, known as pcbA1, pcbA4, and pcbA5, were identified in Dehalococcoides mccartyi strains CG1, CG4, and CG5, respectively (Wang et al 2014). These RDases are similar to RDases found in D. mccartyi strains 195, GT, and JNA, although D. mccartyi strain CBDB1 shares no pcbA1, pcbA4, and pcbA5 orthologs (Bedard 2014). …”

Section: Introductionmentioning

confidence: 54%

PCB dechlorination hotspots and reductive dehalogenase genes in sediments from a contaminated wastewater lagoon

Mattes

Ewald

Liang

et al. 2017

Environ Sci Pollut Res

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Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that are distributed worldwide. Although industrial PCB production has stopped, legacy contamination can be traced to several different commercial mixtures (e.g., Aroclors in the USA). Despite their persistence, PCBs are subject to naturally occurring biodegradation processes, although the microbes and enzymes involved are poorly understood. The biodegradation potential of PCB-contaminated sediments in a wastewater lagoon located in Virginia (USA) was studied. Total PCB concentrations in sediments ranged from 6.34 to 12,700 mg/kg. PCB congener profiles in sediment sample were similar to Aroclor 1248; however, PCB congener profiles at several locations showed evidence of dechlorination. The sediment microbial community structure varied among samples but was dominated by Proteobacteria and Firmicutes. The relative abundance of putative dechlorinating Chloroflexi (including Dehalococcoides sp.) was 0.01–0.19% among the sediment samples, with Dehalococcoides sp. representing 0.6–14.8% of this group. Other possible PCB dechlorinators present included the Clostridia and the Geobacteraceae. A PCR survey for potential PCB reductive dehalogenase genes (RDases) yielded 11 sequences related to RDase genes in PCB-respiring Dehalococcoides mccartyi strain CG5 and PCB-dechlorinating D. mccartyi strain CBDB1. This is the first study to retrieve potential PCB RDase genes from unenriched PCB-contaminated sediments.

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Section: Introductionmentioning

confidence: 54%

PCB dechlorination hotspots and reductive dehalogenase genes in sediments from a contaminated wastewater lagoon

Mattes

Ewald

Liang

et al. 2017

Environ Sci Pollut Res

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“…The identity and role of microorganisms involved in the RD of chloroorganics have been widely described in several environments ( Löﬄer et al, 2013 ) including contaminated marine sediments ( Kormas et al, 2003 ; Inagaki et al, 2006 ; Pachiadaki et al, 2010 ; Pop Ristova et al, 2015 ). Among known dechlorinating bacteria, Dehalococcoides mccartyi ( Chloroflexi phylum) is considered the most important biomarker of chlorinated ethenes RD ( Maymo-Gatell et al, 1997 ; Löﬄer et al, 2013 ; Hug and Edwards, 2013 ; Bedard, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

Microbiome Dynamics of a Polychlorobiphenyl (PCB) Historically Contaminated Marine Sediment under Conditions Promoting Reductive Dechlorination

2016

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The toxicity of polychlorinated biphenyls (PCB) can be efficiently reduced in contaminated marine sediments through the reductive dechlorination (RD) process lead by anaerobic organohalide bacteria. Although the process has been extensively investigated on PCB-spiked sediments, the knowledge on the identity and metabolic potential of PCB-dechlorinating microorganisms in real contaminated matrix is still limited. Aim of this study was to explore the composition and the dynamics of the microbial communities of the marine sediment collected from one of the largest Sites of National Interest (SIN) in Italy (Mar Piccolo, Taranto) under conditions promoting the PCBs RD. A long-term microcosm study revealed that autochthonous bacteria were able to sustain the PCB dechlorination at a high extent and the successive addition of an external fermentable organic substrate (lactate) caused the further depletion of the high-chlorinated PCBs (up to 70%). Next Generation Sequencing was used to describe the core microbiome of the marine sediment and to follow the changes caused by the treatments. OTUs affiliated to sulfur-oxidizing ε-proteobacteria, Sulfurovum, and Sulfurimonas, were predominant in the original sediment and increased up to 60% of total OTUs after lactate addition. Other OTUs detected in the sediment were affiliated to sulfate reducing (δ-proteobacteria) and to organohalide respiring bacteria within Chloroflexi phylum mainly belonging to Dehalococcoidia class. Among others, Dehalococcoides mccartyi was enriched during the treatments even though the screening of the specific reductive dehalogenase genes revealed the occurrence of undescribed strains, which deserve further investigations. Overall, this study highlighted the potential of members of Dehalococcoidia class in reducing the contamination level of the marine sediment from Mar Piccolo with relevant implications on the selection of sustainable bioremediation strategies to clean-up the site.

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“…Recently, Wang et al identified for the first time the PCB reductive dehalogenases present in three Dehalococcoides strains (Wang et al, 2014 ). Each of these enzymes was shown to reduce dozens of different PCB congeners specifically and leading to different end products (Bedard, 2014 ). These results confirmed preceding results showing that members of the Chloroflexi phylum exhibited specifically a limited range of PCB congener dechlorination capacity (Hiraishi, 2008 ).…”

Section: Introductionmentioning

confidence: 99%

Indirect Evidence Link PCB Dehalogenation with Geobacteraceae in Anaerobic Sediment-Free Microcosms

et al. 2016

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Although polychlorinated biphenyls (PCBs) production was brought to a halt 30 years ago, recalcitrance to degradation makes them a major environmental pollutant at a global scale. Previous studies confirmed that organohalide-respiring bacteria (OHRB) were capable of utilizing chlorinated congeners as electron acceptor. OHRB belonging to the Phyla Chloroflexi and Firmicutes are nowadays considered as the main PCB-dechlorinating organisms. In this study, we aimed at exploring the involvement of other taxa in PCB dechlorination using sediment-free microcosms (SFMs) and the Delor PCB mixture. High rates of congener dehalogenation (up to 96%) were attained in long-term incubations of up to 692 days. Bacterial communities were dominated by Chloroflexi, Proteobacteria, and Firmicutes, among strictly simplified community structures composed of 12 major phyla only. In a first batch of SFMs, Dehalococcoides mccartyi closely affiliated with strains CG4 and CBDB1 was considered as the main actor associated with congener dehalogenation. Addition of 2-bromoethanesulfonate (BES), a known inhibitor of methanogenic activity in a second batch of SFMs had an adverse effect on the abundance of Dehalococcoides sp. Only two sequences affiliated to this Genus could be detected in two (out of six) BES-treated SFMs, contributing to a mere 0.04% of the communities. BES-treated SFMs showed very different community structures, especially in the contributions of organisms involved in fermentation and syntrophic activities. Indirect evidence provided by both statistical and phylogenetic analysis validated the implication of a new cluster of actors, distantly affiliated with the Family Geobacteraceae (Phylum δ-Proteobacteria), in the dehalogenation of low chlorinated PCB congeners. Members of this Family are known already for their dehalogenation capacity of chlorinated solvents. As a result, the present study widens the knowledge for the phylogenetic reservoir of indigenous PCB dechlorinating taxa.

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PCB dechlorinases revealed at last

Cited by 12 publications

References 16 publications

PCB dechlorination hotspots and reductive dehalogenase genes in sediments from a contaminated wastewater lagoon

PCB dechlorination hotspots and reductive dehalogenase genes in sediments from a contaminated wastewater lagoon

Microbiome Dynamics of a Polychlorobiphenyl (PCB) Historically Contaminated Marine Sediment under Conditions Promoting Reductive Dechlorination

Indirect Evidence Link PCB Dehalogenation with Geobacteraceae in Anaerobic Sediment-Free Microcosms

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