FIG. 1.

(A) Phenotype of the S. aureus yhcS antisense strain on tryptic soy agar (TSA) plates during ATc induction. Overnight cultures of S. aureus strains were diluted and plated onto TSA-erythromycin plates with or without the inducer ATc (1 μg/ml) and incubated overnight at 37°C. Lane 1, WCUH29/pYH3 control; lane 2, yhcS antisense strain JSAS909; lane 3, unrelated antisense control. Also shown are growth curves of control strain WCUH29/pYH3 (B) and JSAS909 (C) in TSB containing 5 μg/ml of erythromycin and various concentrations of ATc (in nanograms/milliliter). The cultures were diluted to ∼10⁴ CFU/ml with TSB containing appropriate antibiotics and different concentrations of an inducer (anhydrotetracycline [ATc], at concentrations of 0, 10, 50, 100, 250, or 500 ng/ml). Cell growth was monitored at 37°C by measuring the optical density at 600 nm (OD₆₀₀) every 15 min, with 1 min of mixing before each reading using a SpectraMax plus Spectrophotometer (Molecular Devices). The grow curves represent one of three repeated experiments.