FIG. 3.

(A) DTPA, a synthetic iron chelator, was used to test whether iron depletion of fresh medium was able to induce fusion I. DTPA was added to succinate minimal medium at the concentrations shown. Values are the averages of data from three separate experiments (error bars indicate SD). (B) The ability of ferrous sulfate to suppress induction by B. vietnamiensis G4-conditioned medium was tested. The indicated concentrations of ferrous sulfate were added to conditioned succinate minimal medium. The induction level was determined as described in Materials and Methods. Values are the averages of data from three separate experiments (error bars indicate SD).