Figure 2

Comparison of promoter strengths in different culture media. Strains (JOE3273, JOE3275, JOE3277, and JOE3334) carrying transcriptional fusions of uidA to arabinose-, taurine-, rhamnose-, and melibiose-dependent promoter regions were grown in (A) PYE, (B) LB, (C) M9, or (D) M9 plus casamino acids (M9 + CAA) liquid media for three hours, to mid-log phase, in the presence or absence of appropriate inducers. Cultures were then harvested to measure the levels of beta-glucuronidase (GUS) expression. For M9 + CAA, strains were either first grown in M9 + CAA without glucose (−glu) and then diluted into the same medium with or without inducer; or they were first grown in M9 + CAA supplemented with 0.2% glucose (+glu) and diluted into M9 + CAA supplemented with the inducer [+ inducer (+glu)] or glucose [− inducer (+glu)]. Error bars indicate the standard errors of the mean GUS activities. See Methods for further details.