Starter Grant: Molecular Detection of Diverse Arsenic Transforming Prokaryotes and Their Activities in Estuarine Sediments.

砷被美国环境保护署列为致癌物，该局将饮用水中允许的最高砷含量从50 ppb降至10 ppb，以防止大量癌症死亡和其他疾病。在环境中发现的砷污染物水平与参与砷转化的微生物活动密切相关。研究了不同的微生物分离物，以了解砷生物转化的生理和遗传学。然而，环境中砷转化的原位微生物活动尚未得到很好的记录，未开垦的砷转化物的多样性尚未得到充分阐明。人们已经开发出分子工具来检测环境样品中的砷变形，并确定切萨皮克湾沉积物中存在各种未培养的砷转化细菌。在以往研究的基础上，本项目将通过量化编码砷转化的功能基因来确定砷转化的原位微生物活性。此外，将利用环境基因组学方法研究沉积物群落中未培养的本地砷转化微生物的基因组多样性。因此，本研究将更好地了解自然沉积物中与砷转化有关的一般微生物多样性和特定相互作用。这项研究更广泛的意义在于对沉积物中砷的动力学有了严格的认识。本研究结果对评价地下水系统中砷的归宿和运移也具有重要意义。这项研究也将支持研究生和本科生（高级荣誉）的教育和培训。

Arsenic is classified as a carcinogen by the U.S. Environmental Protection Agency, which lowered the allowable maximum arsenic levels in drinking water from 50 ppb to 10 ppb to prevent a significant number of cancer death and other illnesses. The levels of arsenic contaminants found in environments are strongly related to microbial activities involved in arsenic transformation. Diverse microbial isolates have been investigated to understand the physiology and genetics of arsenic biotransformation. However, in situ microbial activities of arsenic transformation in the environment have not been well documented and the diversity of uncultivated arsenic transformers has not been fully elucidated. Molecular tools have been developed to detect arsenic transformers from environmental samples and determine the presence of diverse uncultured arsenic-transforming bacteria in Chesapeake Bay sediments. Building upon previous studies, this project will determine in situ microbial activities of arsenic transformation by quantifying the functional genes encoding arsenic transformation. In addition, uncultured indigenous arsenic-transforming microorganisms in sediment communities will be accessed using environmental genomic approaches to examine their genomic diversity. Thus, this proposed research will provide better understanding of general microbial diversity and specific interactions related to arsenic transformation in natural sediments.The broader significance of this research consists of the rigorous insights gained into the dynamics of arsenic in sediments. Results of this research are also of importance to assess the fate and transport of arsenic in groundwater systems. This research will also support the education and training of graduate and undergraduate (senior honors) students.