The effect of co-substrate activation on indigenous and bioaugmented PCB dechlorinating bacterial communities in sediment microcosms

Abstract

Microbial reductive dechlorination by members of the phylum Chloroflexi, including the genus Dehalococcoides, may play an important role in natural detoxification of highly chlorinated environmental pollutants, such as polychlorinated biphenyls (PCBs). Previously, we showed the increase of an indigenous bacterial population belonging to the Pinellas subgroup of Dehalococcoides spp. in Anacostia River sediment (Washington DC, USA) microcosms treated with halogenated co-substrates ("haloprimers"), tetrachlorobenzene (TeCB), or pentachloronitrobenzene (PCNB). The PCNB-amended microcosms exhibited enhanced dechlorination of weathered PCBs, while TeCB-amended microcosms did not. We therefore developed and used different phylogenetic approaches to discriminate the effect of the two different haloprimers. We also developed complementary approaches to monitor the effects of haloprimer treatments on 12 putative reductive dehalogenase (rdh) genes common to Dehalococcoides ethenogenes strain 195 and Dehalococcoides sp. strain CBDB1. Our results indicate that 16S rRNA gene-based phylogenetic analyses have a limit in their ability to distinguish the effects of two haloprimer treatments and that two of rdh genes were present in high abundance when microcosms were amended with PCNB, but not TeCB. rdh gene-based phylogenetic analysis supports that these two rdh genes originated from the Pinellas subgroup of Dehalococcoides spp., which corresponds to the 16S rRNA gene-based phylogenetic analysis.

Remediation of Polychlorinated Biphenyls (PCBs) in Contaminated Soils and Sediment: State of Knowledge and Perspectives

“…Other haloprimers such as tetrachlorobenzene (TeCB), pentachloronitrobenzene (PCNB), tetrabromobisphenol A (TBBPA) have resulted in an increase of native PCB dechlorinating bacteria such as Dehalococcoides sp., Ochrobactrum sp., Parasegetibacter sp., Thermithiobacillus sp., Phenylobacterium sp., and Sphingomonas sp. (Krumins et al, 2009;Park et al, 2011;Li et al, 2016). Biostimulation has also been achieved by using electrochemical techniques to treat the PCB contaminated groundwater or sediment (Chun et al, 2013;Yu et al, 2016).…”

Enhancing tetrabromobisphenol A biodegradation in river sediment microcosms and understanding the corresponding microbial community

“…Using halogenated cosubstrates as haloprimers could stimulate anaerobic dechlorination, because certain bacteria can use halogenated co-substrate as a terminal electron acceptor during the respiratory reductive dehalogenation or dehalorespiration process (Hiraishi, 2008). This respiratory activity may play an important role in detoxifying organohalides released into the environment (Park et al, 2011). Based on these past studies, this research explored a number of cosubstrates to assess their effect on TBBPA biodegradation.…”

Effects of Ferric Oxyhydroxide on Anaerobic Microbial Dechlorination of Polychlorinated Biphenyls in Hudson and Grasse River Sediment Microcosms: Dechlorination Extent, Preferences, Ortho Removal, and Its Enhancement

“…Many studies suggested that the dechlorination of PCBs was controlled by their sediment geochemical properties and/or microbial species ( Wiegel and Wu, 2000 ; Yan et al, 2006 ; Park et al, 2011 ; Payne et al, 2012 ). This is the first observation of complete dechlorination inhibition in Fe(III)-amended Hudson sediment.…”