D.R.S. and M.A.S. greatly appreciate
support from the Department of Energy, Basic Energy Sciences from
grants DEFG029ER14644 and DEFG0296ER14633, respectively. This research
also was supported by the Center for Environmental Molecular Science
(CEMS) at Stony Brook that is funded by the National Science Foundation
(CHE-0221934). We also acknowledge the assistance of Mark A. Randa
(Temple University) for help with culturing A. ferrooxidans, and Sudeep Debnath (Temple University) for help in obtaining the AFM images.