the photoferrotrophic strains Rhodopseudomnas palustris TIE-1 and Rhodobacter ferrooxidans SW2 are purple non-sulfur bacteria and belong to the Alphaproteobacteria. Strain TIE-1 was originally isolated from a freshwater, iron-rich mat in Woods Hole, MA, UAS (Jiao et al., 20005), and strain SW2 was isolated from a freshwater pond mud sample in Schaumburger Wald, Germany (Ehrenreich and Widdel, 1994).