FIG. 3.

Growth of S. oneidensis MR-1 in phosphate-free M1 medium with 8 mM Fe(III)-NTA as the electron acceptor and 30 mM lactate as the electron donor and carbon source. (A and B) NaH₂PO₄ · H₂O (A) and DNA (B) were used at concentrations of 60 mg/liter and 100 mg/liter, respectively. Filter-sterilized DNA was added to the medium after autoclaving. (C) Growth and Fe(III) reduction in the absence of a P source. ▪, cell numbers; ○, Fe²⁺ concentrations.