Fig 1.

NDFO of mixed soluble and insoluble Fe(II) is not inducible, but Fe(II) is toxic to nitrate-reducing A. ebreus. (a) Concentration of Fe(II) (soluble and vivianite) in chloramphenicol-treated washed cell suspensions of A. ebreus. Cells were pregrown organotrophically (10 mM acetate, 10 mM nitrate) in the absence of Fe(II) or under NDFO conditions in the presence of Fe(II)-NTA [10 mM Fe(II)-NTA, 5 mM acetate, 10 mM nitrate]. (b) Growth expressed as optical density at 600 nm (OD 600) in organotrophic cultures (5 mM acetate, 10 mM nitrate) of A. ebreus containing 0, 0.01, or 0.1 mM Fe(II). Points represent averages of triplicates, and error bars represent standard deviations.