Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan.
National Institute for Land and Infrastructure Management, Tsukuba 305-0804, Japan.
Int J Environ Res Public Health. 2019 Aug 11;16(16):2873. doi: 10.3390/ijerph16162873.
Anoxic aquifers suffer from energy limitations due to the unavailability of organic substrates, as dictated by hydrogen (H) for various electron-accepting processes. This deficiency often results in the accumulation of persistent organic pollutants, where bioremediation using organic compounds often leads to secondary contamination. This study involves the reductive dechlorination of pentachlorophenol (PCP) by dechlorinators that do not use H directly, but rather through a reduced state of humin-a solid-phase humic substance-as the extracellular electron donor, which requires an organic donor such as formate, lactate, etc. This shortcoming was addressed by the development of an anaerobic mixed culture that was capable of reductively dechlorinating PCP using humin under autotrophic conditions induced by homoacetogenesis. Here, H was used for carbon-dioxide fixation to acetate; the acetate produced was used for the reduction of humin; and consequently used for dechlorination through reduced humin. The 16SrRNA gene sequencing analysis showed Dehalobacter and Dehalobacterium as the possible dechlorinators, while Clostridium and Oxobacter were identified as the homoacetogens. Thus, this work contributes to the development of an anaerobic consortium that balanced H dependency, where efficiency of humin reduction extends the applicability of anaerobic microbial remediation in aquifers through autotrophy, syntrophy, and reductive dechlorination.
缺氧含水层由于缺乏有机底物（由氢决定）而受到能量限制，这限制了各种电子受体过程。这种不足通常会导致持久性有机污染物的积累，而使用有机化合物进行生物修复往往会导致二次污染。本研究涉及使用不直接使用 H，而是通过腐殖质的还原态（固相腐殖质）作为细胞外电子供体的脱氯剂还原五氯苯酚（PCP），这需要使用甲酸盐、乳酸盐等有机供体。为了解决这个问题，开发了一种厌氧混合培养物，它能够在同型产乙酸作用诱导的自养条件下使用腐殖质还原脱氯 PCP。在这里，H 用于二氧化碳固定为乙酸；产生的乙酸用于还原腐殖质；随后，通过还原腐殖质用于脱氯。16SrRNA 基因测序分析表明，Dehalobacter 和 Dehalobacterium 可能是脱氯剂，而 Clostridium 和 Oxobacter 被鉴定为同型产乙酸菌。因此，这项工作有助于开发一种厌氧联合体，该联合体平衡了 H 的依赖性，腐殖质的还原效率通过自养、共生和还原脱氯扩展了厌氧微生物修复在含水层中的应用。
