Evidence of Reductive Dechlorination and Mineralization of Lower Chlorinated Biphenyls by Anaerobic Microbial Consortia

多氯联苯(PCbs)是一种广泛优先的有毒污染物，在环境中具有持久性，并易于生物积累。该项目的第一阶段将进行研究，以调查由Grand River Technologies，Inc.实验室开发的厌氧微生物协会对较低氯化多氯联苯定义的同系物的还原脱氯和矿化作用。在过去，还原脱氯过程会导致邻氯化同系物的积累。他们目前的研究表明，MBI厌氧颗粒能够脱除多氯联苯混合物和同系物中的所有氯取代物。氯化程度较高的同系物被广泛地脱氯，但在这些研究中没有看到相应的轻度氯化产物的积累。联苯作为中间产品或最终产品的累积不一致，因此很难计算物质平衡。这些结果很耐人寻味，因为人们普遍认为低氯联苯和联苯不会在厌氧条件下进一步脱氯和矿化。由于他们的结果有力地表明了这一过程的存在，他们打算获得证据来证明这一点。此外，如果这种情况正在发生，那么他们想要了解它的主要机制。根据这项建议的第一阶段，2-氯联苯、2，6-二氯联苯和联苯及其14C标记同位素的命运将在不同条件下与其厌氧微生物群一起进行检测。还将寻求酶证据来确定厌氧条件下环断裂的机制。最终的策略将是利用这些厌氧联合体开发一种就地生物修复工艺来处理被多氯联苯污染的湖泊或河流沉积物。该项目将首次展示厌氧微生物群对多氯联苯的完全脱氯和矿化作用。

Polychlorinated biphenyls (PCBs) are widespread priority toxic pollutants, which are persistent in the environment and tend to bioaccumulate. Phase I of this project will undertake studies to investigate the reductive dechlorination and mineralization of lower chlorinated PCB-defined congeners by anaerobic microbial consortia developed in Grand River Technologies, Inc. laboratory. In the past, reductive dechlorination processes have resulted in the accumulation of ortho-chlorinated congeners. Their current investigations have indicated that the MBI anaerobic granules are capable of dechlorinating all substitutions of chlorines from PCB mixtures and congeners. Higher chlorinated congeners were dechlorinated extensively, but accumulation of corresponding lightly chlorinated products was not seen in these studies. Accumulation of biphenyl as an intermediate or end product was inconsistent and thus, it is difficult to calculate a material balance. These results are intriguing since it is widely accepted that lower chlorinated biphenyls and biphenyl do not undergo further dechlorination and mineralization anaerobically. Since their results strongly indicate that process exists, they intend to obtain evidence to prove it. Further if that is happening then they want to understand the primary mechanism for it. Under Phase I of this proposal, the fate of 2-Chlorobiphenyl, 2,6-Dichloribiphenyl and Biphenyl, and their 14C-labeled isotopes will be examined with their anaerobic microbial consortia under different conditions. Enzymatic evidence will also be sought to determine the mechanism of ring cleavage under anaerobic condition. The ultimate strategy will be to utilize these anaerobic consortia to develop an in situ bioremediation process to treat PCB-contaminated lake or river sediments. This project will be the first demonstration of complete dechlorination and mineralization of PCBs by anaerobic microbial consortia.