Primary and corrected data. (a) Absorbance and fluorescence intensity measured on a population of bacteria carrying the GFP reporter system of Fis. (b) Absorbance and fluorescence intensity corrected for background levels. (c)-(d) Idem for the luciferase reporter system of Fis. The measurements are represented by blue circles (fluorescence or luminescence) and red crosses (absorbance), and the spline fits are indicated by solid lines. The dashed lines delimit the 95% confidence bands.