FIG. 2.

Growth phenotypes of strains of B. subtilis 168 (B. sub 168) harboring the synthetic promoter-nisFEGI-lacZ construct (A) and characterization of the strengths of the different synthetic promoters (SP) (B). All strains were grown in LB medium at 37°C, and cell growth was measured at 600 nm. The β-galactosidase activity (expressed in Miller units [MU]) is plotted against the time of delay. Samples for the β-galactosidase assay were taken from cultures at an OD₆₀₀ of 0.5, after which 600 ng/ml of nisin was added to the cultures and the time of delay was calculated as the time from the addition of nisin until the cells reached an OD₆₀₀ of 0.5 again. The black arrows indicate the time of the nisin addition.