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. 2007 Aug 10;73(19):6150–6158. doi: 10.1128/AEM.02830-06

FIG. 1.

FIG. 1.

Anoxygenic phototrophic Fe(II) oxidation and phototrophic growth on Fe(III)-citrate by R. capsulatus SB1003. (A) R. capsulatus SB1003 can perform phototrophic Fe(II) oxidation. A cell suspension assay was performed in medium containing 0.5 mM Fe(II). ▴, R. capsulatus SB1003 in the light; •, R. capsulatus SB1003 in the dark; ▪, uninoculated control in the light. (B) R. capsulatus SB1003 cannot grow by Fe(II) oxidation. Protein concentration and Fe(II) concentration were measured over time for cells incubated in the presence of 4 to 6 mM Fe(II). □, R. capsulatus SB1003 in the light; ⧫, uninoculated control in the light; ▴, Fe(II) concentration of the R. capsulatus SB1003 cultures. (C) R. capsulatus SB1003 cannot use citrate as a phototrophic carbon source. Cells were incubated in medium containing 10 mM citrate (•) or 10 mM acetate (▪) and assayed for growth. (D) Phototrophic growth of R. capsulatus SB1003 in the presence of Fe(II)-citrate. Cells were incubated in medium containing 5 mM Fe(III) and 10 mM citrate. Uninoculated controls were prepared and incubated similarly. Over time, aliquots were removed and Fe(II) concentrations were measured. End point protein concentrations were determined for inoculated samples. ⧫, R. capsulatus SB1003 in the light (final protein concentration of ∼139 μg/ml); ×, R. capsulatus SB1003 in the dark (final protein concentration was below detection); ▴, uninoculated control in the light; □, uninoculated control in the dark. Error bars in panels A, B, C, and D show the standard deviations of triplicate cultures.