The γ isomer of hexachlorocyclohexane (HCH), also known as lindane, is a carcinogenic persistent organic pollutant. Lindane was used worldwide as an agricultural insecticide. Legacy soil and groundwater contamination with lindane and other HCH isomers is still a big concern. The biotic reductive dechlorination of HCH to non-desirable and toxic lower chlorinated compounds such as monochlorobenzene (MCB) and benzene, among others, has been broadly documented. Here, we demonstrate for the first time that complete biotransformation of lindane to non-toxic end products is attainable using a sequential treatment approach with three mixed anaerobic microbial cultures referred to as culture I, II, and III. Biaugmentation with culture I achieved dechlorination of lindane to MCB and benzene. Culture II was able to dechlorinate MCB to benzene, and finally, culture III carried out methanogenic benzene degradation. Distinct Dehalobacter populations, corresponding to different 16S rRNA amplicon sequence variants in culture I and culture II, were responsible for lindane and MCB dechlorination, respectively. This study continues to highlight key roles of Dehalobacter spp. as chlorobenzene- and HCH-organohalide-respiring bacteria and demonstrates that sequential treatment with specialized anaerobic cultures may be explored at field sites in order to address legacy soil and groundwater contamination with HCH.

中文翻译：

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通过三种厌氧微生物混合培养物的顺序处理，将林丹（γ-六氯环己烷）生物转化为无毒的最终产品

六氯环己烷（HCH）的γ异构体，也称为林丹，是致癌的持久性有机污染物。林丹在世界范围内被用作农业杀虫剂。林丹和其他六氯环己烷异构体对旧土壤和地下水的污染仍然是一个大问题。六氯环己烷经过生物还原性脱氯反应后，生成了不良的，有毒的低级氯化物，例如一氯苯（MCB）和苯等。在这里，我们首次证明了使用序贯处理方法，将三种混合厌氧微生物培养物称为培养物I，II和III，可以实现林丹完全生物转化为无毒的最终产品。与培养物的分离我实现了将林丹脱氯为MCB和苯。Culture II能够将MCB脱氯为苯，最后，培养物III进行了产甲烷苯的降解。分别与培养物I和培养物II中不同的16S rRNA扩增子序列变体相对应的独特的脱盐细菌群体分别负责林丹和MCB脱氯。这项研究继续强调了Dehalobacter spp的关键作用。作为氯气和六氯环己烷可吸入有机卤化物的细菌，证明了可以在田间地点探索采用专门的厌氧培养物进行顺序处理，以解决六氯环己烷对土壤和地下水的污染问题。这项研究继续强调了Dehalobacter spp的关键作用。作为氯气和六氯环己烷可吸入有机卤化物的细菌，证明了可以在田间地点探索采用专门的厌氧培养物进行顺序处理，以解决六氯环己烷对土壤和地下水的污染问题。这项研究继续强调了Dehalobacter spp的关键作用。作为氯气和六氯环己烷可吸入有机卤化物的细菌，证明了可以在田间地点探索采用专门的厌氧培养物进行顺序处理，以解决六氯环己烷对土壤和地下水的污染问题。