Fig 1.

Promoter strength and translation efficiency of z0321, z1789, and z2104. β-Galactosidase activities from translational lacZ fusions of z0321, z1789, and z2104 were determined in both the exponential and stationary phases. β-Galactosidase activity is expressed in Miller units as defined by Miller (37). Data are means and standard deviations for three independent experiments carried out in duplicate. (A) The various EDL933(Δstx1-2) derivatives were either grown in LB at 37°C to an OD₆₀₀ of ∼0.6 (exponential phase) or harvested after incubation for 22 h (stationary phase). (B) Analysis of z0321 expression over a period of 22 h.