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

多氯联苯（PCBs）是一种广泛存在的优先毒性污染物，在环境中具有持久性和生物累积性。该项目的第一阶段将开展研究，调查格兰德河技术公司开发的厌氧微生物联合体对低氯化多氯联苯确定的同系物的还原脱氯和矿化作用。实验室过去，还原脱氯工艺导致邻氯同系物的积累。他们目前的研究表明，MBI厌氧颗粒能够将多氯联苯混合物和同系物中的所有氯替代物脱氯。在这些研究中，高氯化同系物被广泛地脱氯，但相应的轻度氯化产物并未积累。作为中间产品或最终产品的联苯的累积不一致，因此难以计算物料平衡。这些结果是有趣的，因为人们普遍认为，低氯联苯和联苯不经历进一步的脱氯和矿化厌氧。由于他们的研究结果强烈表明该过程存在，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，他们希望了解其主要机制。在该提案的第一阶段，2-氯联苯，2，6-二氯联苯和联苯，以及它们的14 C标记同位素的命运将在不同条件下用厌氧微生物财团进行检查。酶的证据也将寻求确定在厌氧条件下的环断裂的机制。最终的战略将是利用这些厌氧联合体来开发一种就地生物修复过程，以处理受多氯联苯污染的湖泊或河流沉积物。该项目将是第一个通过厌氧微生物联合体对多氯联苯进行完全脱氯和矿化的示范项目。

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.