Comparison of mean single cell fluorescence and apparent growth rate at different extracellular CAM concentrations.

<p>Mean calcein fluorescence for five extracellular CAM concentrations are shown for five cultivation chambers each (every chamber is indicated with a separate colour). Perfusion medium was switched from CGXII + 4% GLC to carbon free CGXII medium (CGXII—PCA) supply for 10 h (indicated with red frame) to inhibit the energy-dependent calcein efflux. CAM conversion by intracellular esterase activity and subsequent calcein fluorescence showed a non-linear fluorescence increase except for concentrations higher than the optimal extracellular CAM concentration of 46 μM. The corresponding apparent growth rates changed according to the carbon supply and not because of an increase CAM concentration.