The Microbiology of Anaerobic PCB Dechlorination

  • Jianzhong HeEmail author
  • Donna L. BedardEmail author


The last few years have seen a great deal of progress in our understanding of microbial dechlorination of polychlorinated biphenyls (PCBs). Four new strains of Dehalococcoides mccartyi, representing all three phylogenetic subgroups, and a strain of “ Dehalobium chlorocoercia ” have been isolated and, together with two previously isolated strains of D. mccartyi , demonstrated to dechlorinate the commercial PCB mixture Aroclor 1260 . Complete genomes for five of these isolates have been published. In addition, members of the genera Dehalogenimonas and Dehalobacter have been implicated in the reductive dechlorination and respiration of PCBs. It is clear that D. mccartyi strains capable of dechlorinating Aroclor 1260 are widespread in freshwater environments, having been found in PCB-impacted sites in China, Germany, Singapore, and the USA. Pure strains of D. mccartyi that dechlorinate Aroclor 1260 by following different sets of dechlorination routes, i.e., PCB Dechlorination Processes H, N,Z, and variations of these are now available. A member of the Chloroflexi belonging to the m1/SF1 clade appears to be responsible for the dechlorination of Aroclor 1254 in a marine site. The discovery and characterization of the first three PCB reductive dehalogenases constitute a new milestone in the field. PcbA1 , PcbA4 , and PcbA5 dechlorinate Aroclor 1260 with distinct regiospecificities and prove that individual RDases can carry out the complex dechlorination of dozens of PCB congeners described by the PCB dechlorination processes . Each of these three PCB dechlorinases is bifunctional and can also dechlorinate tetrachloroethene (PCE ). PCB dechlorinators with such bifunctional PCB/PCE RDases can be selectively enriched, transferred repeatedly, and grown to high cell densities with PCE as the sole electron acceptor with no possibility of losing their ability to dechlorinate PCBs. This property makes them ideal candidates for use in bioremediation of PCBs.


Reductive Dechlorination Dechlorination Process Reductive Dehalogenase Sole Electron Acceptor Dechlorination Product 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Department of Civil and Environmental EngineeringNational University of SingaporeSingaporeSingapore
  2. 2.Department of Biological SciencesRensselaer Polytechnic InstituteTroyUSA

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