Chloroethenes are common soil and groundwater pollutants. Their dechlorination is impacted by environmental factors, such as the presence of metal ions. We here investigated the effect of ferrous iron on bacterial reductive dechlorination of chloroethenes and on methanogen community. Reductive dechlorination of tetrachloroethene was assayed with a groundwater sample originally containing 6.3 × 10³ copies mL^–1 of Dehalococcoides 16S rRNA gene and 2 mg L^–1 of iron. Supplementation with 28 mg L^–1 of ferrous iron enhanced the reductive dechlorination of cis-dichloroethene (cis-DCE) and vinyl chloride in the presence of methanogens. The supplementation shortened the time required for complete dechlorination of 1 mg L^–1 of tetrachloroethene to ethene and ethane from 84 to 49 d. Methanogens, such as Candidatus ‘Methanogranum’, Methanomethylovorans and Methanocorpusculum, were significantly more abundant in iron-supplemented cultures than in non-supplemented cultures (P<<0.01i>). Upon methanogen growth inhibition by 2-bromoethanesulfonate and in the absence of iron supplementation, cis-DCE was not dechlorinated. Further, iron supplementation induced 71.3% dechlorination of cis-DCE accompanied by an increase in Dehalococcoides 16S rRNA and dehalogenase vcrA gene copies but not dehalogenase tceA gene copies. These observations highlight the cooperative effect of iron and methanogens on the reductive dechlorination of chloroethenes by Dehalococcoides spp.

中文翻译：

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补充亚铁离子对四氯乙烯还原脱氯和产甲烷微生物群落的影响

氯乙烯是常见的土壤和地下水污染物。它们的脱氯受环境因素的影响，例如金属离子的存在。我们在这里研究了亚铁对细菌对氯乙烯的还原性脱氯和产甲烷菌群落的影响。四氯乙烯的还原脱氯用原本含有地下水样品6.3×10测定³份毫升^-1的Dehalococcoides 16S rRNA基因和2毫克的L ^-1的铁。补充28 mg L ^–1的亚铁可增强顺式-二氯乙烯（cis）的还原脱氯作用-DCE）和氯甲烷在产甲烷菌的存在下。补充将1 mg L ^–1的四氯乙烯完全脱氯为乙烯和乙烷所需的时间从84 d缩短到49 d。补铁培养物中的产甲烷菌，例如念珠菌“ Methanogranum”，Methanomethylovorans和Methanocorpusculum，明显比未补充培养物中的丰富（P <0.01 i>）。在2-溴乙烷磺酸盐抑制产甲烷菌生长和不添加铁的情况下，顺式-DCE未脱氯。此外，铁的补充导致顺式的71.3％脱氯-DCE伴随着Dehalococcoides 16S rRNA和dehalogenase vcrA基因拷贝的增加，但没有dehalogenase tceA基因拷贝的增加。这些观察结果突出了铁和产甲烷菌对Dehalococcoides spp对氯乙烯的还原性脱氯作用的协同作用。