State Key Laboratory of Organic Geochemistry and Guangdong-Hong Kong-Maco Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
State Key Laboratory of Organic Geochemistry and Guangdong-Hong Kong-Maco Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Pollut. 2023 Dec 1;338:122704. doi: 10.1016/j.envpol.2023.122704. Epub 2023 Oct 6.
End-of-life vehicles (ELVs) dismantling sites are the notorious hotspots of chlorinated organophosphate esters (Cl-OPEs). However, the microbial-mediated dechlorination of Cl-OPEs at such sites has not yet been explored. Herein, the dechlorination products, pathways and mechanisms of tris(2-chloroethyl) phosphate (TCEP, a representative Cl-OPE) by an anaerobic enrichment culture (ZNE) from an ELVs dismantling plant were investigated. Our results showed that dechlorination of TCEP can be triggered by reductive transformation to form bis(2-chloroethyl) phosphate (BCEP), mono-chloroethyl phosphate (MCEP) and by hydrolytic dechlorination to form bis(2-chloroethyl) 2-hydroxyethyl phosphate (TCEP-OH), 2-chloroethyl bis(2-hydroxyethyl) phosphate (TCEP-2OH), 2-chloroethyl (2-hydroxyethyl) hydrogen phosphate (BCEP-OH). The combination of 16S rRNA gene amplicon sequencing, quantitative real-time PCR (qPCR) and metagenomics revealed that the Dehalococcoides played an important role in the reductive transformation of TCEP to BCEP and MCEP. A high-quality metagenome-assembled genome (completeness >99% and contamination <1%) of Dehalococcoides was obtained. The sulfate-reducing bacteria harboring haloacid dehalogenase genes (had) may be responsible for the hydrolytic dechlorination of TCEP. These findings provide insights into microbial-mediated anaerobic transformation products and mechanisms of TCEP at ELVs dismantling sites, having implications for the environmental fate and risk assessment of Cl-OPEs at those sites.
报废车辆（ELV）拆解场地是含氯有机磷酸酯（Cl-OPEs）的臭名昭著的热点区域。然而，这种场地中微生物介导的 Cl-OPEs 脱氯作用尚未得到探索。在此，研究了从 ELV 拆解厂的厌氧富集培养物（ZNE）中三（2-氯乙基）磷酸酯（TCEP，一种代表性的 Cl-OPE）的脱氯产物、途径和机制。我们的研究结果表明，TCEP 的脱氯作用可以通过还原转化引发，形成双（2-氯乙基）磷酸酯（BCEP）、单氯乙基磷酸酯（MCEP）和水解脱氯形成双（2-氯乙基）2-羟乙基磷酸酯（TCEP-OH）、2-氯乙基双（2-羟乙基）磷酸酯（TCEP-2OH）、2-氯乙基（2-羟乙基）磷酸氢盐（BCEP-OH）。16S rRNA 基因扩增子测序、定量实时 PCR（qPCR）和宏基因组学的组合揭示了 Dehalococcoides 在 TCEP 向 BCEP 和 MCEP 的还原转化中发挥了重要作用。获得了一个高质量的 Dehalococcoides 宏基因组组装基因组（完整性>99%，污染<1%）。可能含有 haloacid 脱卤酶基因（had）的硫酸盐还原菌负责 TCEP 的水解脱氯。这些发现为 ELV 拆解场地中 TCEP 的微生物介导的厌氧转化产物和机制提供了深入了解，对这些场地中 Cl-OPEs 的环境命运和风险评估具有重要意义。
