FIG. 3.

Analysis of sil promoter expression. (A) Response to temperature. Overnight cultures of the wild-type strain carrying the sil promoter construct were grown at 37°C and 30°C (*, P < 0.0001). (B) Response to oxygen tension and agitation. The HSC5 wild-type strain carrying the sil promoter construct was cultured in 10 ml of TP under the following conditions: in a 15-ml conical tube without shaking, in a 15-ml conical tube with shaking, or in a 50-ml flask with shaking overnight (*, P < 0.0001). (C) Response to H₂O₂ treatment. The wild-type strain carrying the sil promoter construct was grown to mid-log phase and then treated with 5 mM or 7 mM H₂O₂ for 2 h at 37°C (*, P < 0.001). (D) Response to growth phase. The wild-type strain (dark gray bars), the silC mutant strain (light gray bars), and the silB mutant strain (black bars) carrying the sil promoter construct were assayed for activity at different times during growth.