Growth of Dehalococcoides spp. and increased abundance of reductive dehalogenase genes in anaerobic PCB-contaminated sediment microcosms

Long-Term Dechlorination of Polychlorinated Biphenyls (PCBs) in Taihu Lake Sediment Microcosms: Identification of New Pathways, PCB-Driven Shifts of Microbial Communities, and Insights into Dechlorination Potential

“…The 16S rRNA gene of Dehalococcoides detected in this study was as high as 10 7 copies/mL by the end of the incubation, which was direct evidence for the long-term dechlorination potential. Recently, a similar observation of 2 orders of magnitude increase to 10 7 copies/g of Dehalococcoides 16S rRNA gene during 430 days demonstrated the PCB dechlorination potential of the native microbial communities . In addition, RDase genes pcb A4 and pcb A5 were enriched to only 10 4 copies/g, while rd 14, highly transcribed from D.…”

“…Recently, a similar observation of 2 orders of magnitude increase to 10 7 copies/g of Dehalococcoides 16S rRNA gene during 430 days demonstrated the PCB dechlorination potential of the native microbial communities. 73 In addition, RDase genes pcbA4 and pcbA5 were enriched to only 10 4 copies/g, while rd14, highly transcribed from D. mccartyi CG5, increased to 10 7 copies/g by the end of the incubation. 18,73 Another two studies reported the presence of pcbA1, pcbA4, and pcbA5 genes with concentrations of 10 4 to 10 6 copies/g in PCB-contaminated marine sediments.…”

“…In addition, RDase genes pcb A4 and pcb A5 were enriched to only 10 4 copies/g, while rd 14, highly transcribed from D. mccartyi CG5, increased to 10 7 copies/g by the end of the incubation. , Another two studies reported the presence of pcb A1, pcb A4, and pcb A5 genes with concentrations of 10 4 to 10 6 copies/g in PCB-contaminated marine sediments. , The copies of pcb A4 and pcb A5 genes per mL (10 7 ) in our study were much higher than previous studies. The presence and concentrations of RDase genes had been used as biomarkers to monitor dechlorination activity in contaminated sites. , In the present study, the amount of four RDase genes all increased to 10 7 copies/mL slurry, supporting the continuous dechlorination potential of the Taihu Lake sediment.…”

Metagenomes, Metagenome-Assembled Genomes, and Metatranscriptomes from Polychlorinated Biphenyl-Contaminated Sediment Microcosms

“…Polychlorinated biphenyl (PCB)-contaminated sediments threaten human and ecological health but often harbor PCB-transforming bacteria that help detoxify sediments ( 1 – 3 ). We established anaerobic microcosms, as described previously ( 4 , 5 ), to investigate anaerobic microbiomes native to PCB-contaminated lagoon sediments. Replicate microcosms contained sediments, collected in 2017, from two different locations (four bottles total) with variable PCB concentrations (28.04 ± 2.89 μg/mL [high-PCB microcosms [HPCBM], F4_1 and F4_2] versus 4.28 ± 1.05 μg/mL [low-PCB microcosms [LPCBM], E2_1 and E2_2]; P < 0.0001).…”

“…Bin completeness, contamination, and strain heterogeneity statistics were generated by CheckM (v1.1.3), and bin taxonomy was refined with Kraken2 ( 12 – 14 ) ( Table 1 ). Among the MAGs, bin 47 ( Dehalococcoides mccartyi ) ( Table 1 ), which was previously implicated in PCB dechlorination ( 4 ), is expected to harbor PCB dehalogenase genes.…”