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.
