Identification of Key Microbial Players Carrying Out Reductive Dechlorination of PCBs in Freshwater Sediments

多氯联苯（PCBs）是水体沉积物中广泛存在的污染物。 在许多这些受污染的沉积物中的厌氧微生物有能力去除多氯联苯中的氯。 脱氯可降低多氯联苯的持久性和潜在毒性。到目前为止，还没有发现任何脱氯微生物，因此对其生态或多氯联苯脱氯酶/途径的演变一无所知。先前的研究表明，多氯联苯脱氯微生物存在于胡萨托尼克河（莱诺克斯，马萨诸塞州），它们表现出三种不同的多氯联苯脱氯活动。 这些活动中的每一个都有不同的底物，目标氯位置，pH值和温度最佳。 该研究项目将利用分子技术来确定当这些不同的活动被刺激和富集时微生物群落结构发生的关键变化，并将利用基于16 S rRNA的系统发育分析来确定进行多氯联苯还原脱氯的关键微生物参与者。 长期目标包括分离多氯联苯脱氯细菌，并分离和鉴定其多氯联苯脱氯酶。 这项研究将扩大我们对一个重要的环境过程和厌氧沉积物群落的理解。

Polychlorinated biphenyls (PCBs) are widespread contaminants of aquatic sediments. Anaerobic microorganisms in many of these contaminated sediments have the capacity to remove chlorine from the PCBs. Dechlorination reduces the persistence and potential toxicity of PCBs. To date, none of the dechlorinating microorganisms have been identified and thus nothing is known about their ecology or about the evolution of PCB-dechlorinating enzymes/pathways. Previous studies have shown that PCB-dechlorinating microorganisms are present in the Housatonic River (Lenox, MA) and that they exhibit three distinct PCB-dechlorinating activities. Each of these activities has distinct substrates, targeted chlorine positions, and pH and temperature optima. This research project will use molecular techniques to identify the key changes in microbial community structure that occur when these different activities are stimulated and enriched and will use 16S rRNA-based phylogenetic analysis to identify the key microbial players carrying out reductive dechlorination of PCBs. Long-term goals include isolation of PCB-dechlorinating bacteria and isolation and characterization of their PCB-dechlorinating enzymes. This research will expand our understanding of an important environmental process and of anaerobic sediment communities.