Isolation and Characterization of PCB Dechlorinators

多氯联苯因其化学稳定性和疏水性而具有顽固性。在被印刷电路板污染的地方 沉淀物，生物介导式脱氯可降低毒性，减少 生物积累。然而，在环境中，这些化合物生物降解缓慢且不完全，使得固有的生物修复不太适合于多氯联苯污染场地的管理。我们一直在研究一种技术，以刺激受污染沉积物中多氯联苯的原位还原脱氯。目前，天然样品中的多氯联苯脱氯微生物总数无法量化；因此，我们无法确定浓缩和/或刺激技术是否会导致环境中脱氯细菌的生长。如果确定了这些生物体，就可以开发基于分子的技术来确定特定地点存在哪些生物体，以及它们的数量如何随时间变化。此外，在没有多氯联苯脱氯细菌分离株或高度浓缩和定义的脱氯微生物培养物的情况下，我们对多氯联苯脱氯的生理学(例如，生长和生物降解率、营养需求等)的了解。因此，我们设计沉积物生物修复系统的努力受到很大阻碍。在这项拟议的研究中，我们将：(1)开发高度浓缩的多氯联苯脱氯培养物(2-3个种群)或从巴尔的摩港、哈德逊河、帕洛斯韦尔德斯和沃克贡港沉积物中获得多氯联苯脱氯分离物，并鉴定存在的脱氯菌；(2)调查这些微生物的氢亲和力和阈值、电子供体专一性、电子受体专一性和多氯联苯同系物专一性。

PCBs are recalcitrant due their chemical stability and hydrophobicity. In PCB-contaminated sediments, biologically-mediated dechlorination results in reduced toxicity and less bioaccumulation. In the environment, however, these compounds biodegrade slowly and incompletely, making intrinsic bioremediation less desirable for the management of PCB-contaminated sites. We have been working on a technology to stimulate the in situ reductive dechlorination of PCBs in contaminated sediment. Presently, the total number of PCB-dechlorinating microbes in natural samples cannot be quantified; therefore, we cannot determine whether enrichment and/or stimulation techniques result in the growth of dechlorinating bacteria in the environment. If these organisms are identified, molecular-based techniques could be developed to determine which organisms are present at a particular site and how their numbers change with time. In addition, without PCB-dechlorinating bacterial isolates or highly enriched and defined dechlorinating microbial cultures, our Understanding of the physiology of PCB-dechlorination (e.g., growth and biodegradation rates, nutritional needs, etc.) is limited, and thus our efforts to engineer a sediment bioremediation system are significantly hampered. In this proposed research we will: (1) develop highly enriched PCB-dechlorinating cultures (2-3 populations) or obtain PCB-dechlorinating isolates from Baltimore Harbor, Hudson River, Palos Verdes, and Waukegon Harbor sediment and identify the dechlorinators present, and (2) investigate the H2 affinity and threshold, electron donor specificity, electron acceptor specificity, and PCB congener specificity of these organisms.