Optical density (OD) measurements were performed at 600 nm (SPEKOL 1300; Analytik Jena,
Germany) with freshly inoculated Fe(II)-free medium and 5 mM acetate as electron donor. To
determine influence of UVR on Fe(II) oxidation rates, non-irradiated and irradiated samples
were used to inoculate fresh medium containing Fe(II) as the electron donor. Samples for iron
quantification were then taken over different time intervals to ascertain Fe(II) oxidation rates.