An Fe(II)-containing medium was prepared by adding a 1 M FeCl2 stock solution to a concentration of 10mM and filtering the medium after storage for 48 h at 4 C to remove Fe(II) precipitates, leading to a final concentration of 8 mM of dissolved Fe (II) for low phosphate mineral medium or 4 mM for mineral medium. Photoferrotrophic strains were cultivated either with Fe(II) as electron donor or in Fe(II)-free medium with 5 mM sodium acetate or H2 supplemented to the headspace as a H2/CO2 mixture (90:10v/v) under constant light conditions (True light 15W/5500K) at 20 C