Offshore Marine Sediment Microbiota Respire Structurally Distinct Organohalide Pollutants

Abstract

Marine sediments are a major sink of organohalide pollutants, but the potential for offshore marine microbiota to transform these pollutants remains underexplored. Here, we report dehalogenation of diverse organohalide pollutants by offshore marine microbiota. Dechlorination of polychlorinated biphenyls (PCBs) was observed in four marine sediment microcosms, which was positively correlated with in situ PCB contamination. Three distinct enrichment cultures were enriched from these PCB-dechlorinating microcosms using tetrachloroethene (PCE) as the sole organohalide. All enrichment cultures also dehalogenated polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A (TBBPA), and 2,4,6-trichlorophenol (2,4,6-TCP). Particularly, two enrichments completely debrominated penta-BDEs, the first observation of complete debromination of penta-BDEs in marine cultures. Multiple Dehalococcoides and uncultivated Dehalococcoidia were identified in the initial sediment microcosms, but only Dehalococcoides was dominant in all enrichments. Transcription of a gene encoding a PcbA5-like reductive dehalogenase (RDase) was observed during dehalogenation of different organohalides in each enrichment culture. When induced by a single organohalide substrate, the PcbA5-like RDase dehalogenated all tested organohalides (PCE, PCBs, PBDEs, TBBPA, and 2,4,6-TCP) in in vitro tests, suggesting its involvement in dehalogenation of structurally distinct organohalides. Our results demonstrate the versatile dehalogenation capacity of marine Dehalococcoidia and contribute to a better understanding of the fate of these pollutants in marine systems.

Efficient and Complete Detoxification of Polybrominated Diphenyl Ethers in Sediments Achieved by Bioaugmentation with Dehalococcoides and Microbial Ecological Insights

“…mccartyi strains CG1, 11a, and TZ50, respectively (Table S2). ,,− The temperature program of qPCR included an initial denaturation step at 98 °C for 3 min and 40 cycles of 98 °C for 15 s and 60 °C for 30 s. Standard curves (10 2 –10 8 gene copies/μL) were prepared by serial dilution of known concentration of plasmids containing the target genes constructed as previously described . Nuclease-free water was used as the negative control.…”

Marine Dehalogenator and Its Chaperones: Microbial Duties and Responses in 2,4,6-Trichlorophenol Dechlorination

“…Sediment samples were collected from the coast of the East China Sea (29.40°N, 122.25°E) using a stainless steel Gray O’Hara box corer during the Dongfanghong-2 cruise in March 2017. The microcosms were set up as previously described . Unless otherwise stated, the anaerobic mineral salts (AMS) medium was supplemented with 10 mM lactate and 25 μM TCP.…”

Tritium and Carbon-14 Contamination Reshaping the Microbial Community Structure, Metabolic Network, and Element Cycle in the Seawater Environment

“…Tritium can be stored in organisms as tissue-free water tritium (TFWT) and organically bound tritium (OBT). , High-concentration tritium exposure activates microalgal cells’ reactive oxygen species (ROS) signaling pathway. It adversely affects cell growth and metabolism, while carbon-14 can quickly enter marine sediments and be absorbed by marine organisms. − Marine ecosystems rely on microorganisms and microalgae to mediate carbon, nitrogen, phosphorus, sulfur, and pollutant degradation cycles. − Therefore, tritium and carbon-14 pollution can have severe ecological risks in marine environments.…”