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

多氯联苯是水体沉积物中广泛存在的污染物。其中许多受污染沉积物中的厌氧微生物具有从多氯联苯中去除氯的能力。脱氯降低了多氯联苯的持久性和潜在的毒性。到目前为止，还没有鉴定出任何脱氯微生物，因此对它们的生态或多氯联苯脱氯酶/途径的进化一无所知。先前的研究表明，Housatonic河(马萨诸塞州勒诺克斯)中存在多氯联苯脱氯微生物，它们表现出三种不同的多氯联苯脱氯活动。每一种活性都有不同的底物，有针对性的氯位置，以及最适的pH和温度。这项研究项目将使用分子技术来确定当这些不同的活动被刺激和丰富时发生的微生物群落结构的关键变化，并将使用基于16S 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分子。长期目标包括分离多氯联苯脱氯细菌及其多氯联苯脱氯酶的分离和特性。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.