Figure 4

E. coli growth with toxic gene expression under the control of P _fhuA1 . A. Growth curves to demonstrate the tightly controllable expression of lysis gene E in p_tP_fhuA1E, p_bP_fhuA1E and p_aP_fhuA1E under repression (+Fe, 40 μM FeSO₄), or induction (+DP, 200 μM 2,2’dipyridyl). At −3 h, 40 μM FeSO₄ was added; at 0 h, 200 μM 2,2’dipyridyl was added. Cultures were in duplicate. Bacterial growth was measured at OD₆₀₀ nm. B. Colony forming units of Top10/p_atP_fhuA1gef and Top10/p_atP_fhuA1mazF after induction. At 0 h, 200 μM 2,2’dipyridyl was added. The error bars represent the standard deviation (SD) for three independent experiments, performed in triplicate.