FIG 2.
Mutants with reduced σE activity outcompete the parental ΔrseA strain in stationary-phase cultures. (A and B) OD600 (A) and CFU per milliliter (B) of ΔrseA (blue squares) and wild-type (green squares) cultures grown for 10 days are shown. (C) Total CFU per milliliter of ΔrseA cultures (closed squares) and CFU per milliliter of mutants with reduced σE activity that arose in ΔrseA cultures (open squares) are shown. Data presented are averages with standard deviations from 4 independent cultures. (D) σE overexpression from the plasmid pLC245 also reduces survival in stationary phase. The OD600 values for a wild-type strain carrying pLC245 (blue triangles) or the control plasmid pTrc99a (green circles) grown under inducing conditions in the absence of selective pressure for the plasmids are shown as open symbols. The total CFU per milliliter (closed symbols, dashed lines) and the CFU per milliliter of cells still carrying the plasmid, as measured by ampicillin resistance (closed symbols, solid lines), are shown for each strain.