Regulation of Arsenic Metabolism of Shewenella sp. ANA-3

Arsenate respiration in microbes found in the soil surrounding ground water sources can enhance arsenic release from naturally occurring arsenic-bearing minerals. Once liberated, the reduced form of arsenic (arsenite) can contaminate ground water sources posing a significant health risk to those utilizing this source of water and is a problem around the world. In the present research, a model metal reducing bacteria is used, Shewenella sp. strain ANA-3, which is a facultative anaerobe that is able to reduce arsenic using the arsenate respiratory reductase (ArrA) as well as detoxify arsenic from its system using the arsA, arsD, and arsB genes. Involved with the expression of theses genes is the cyclic AMP receptor protein, CRP. Data shows that under anaerobic conditions cAMP is essential for growth on arsenic but how the cell regulates it synthesis is still unknown. The hypothesis is that the Phosphotransferase system (PTS) is involved in cAMP regulation in our model organism since data shows its involvement in cAMP and CRP regulation in E. coli. Utilizing directed gene deletion and transposon mutagenesis this project will identify additional genes essential to the cAMP signaling pathway and arsenic metabolism in general. The goal is that these efforts will lead to a better understanding of the genetic mechanism of arsenic metabolism in Shewenella sp. strain ANA-3. This knowledge can be applied to bioremediation of arsenic contamination in ground water as a result of anaerobic microbial metabolism.