Simultaneous recording of DIC and fluorescence image intensity of individual B. subtilis spores adhered on a coverslip germinating at 37°C with 10 mM L-valine and 35 μg/mL berberine in 25 mM K-HEPES buffer.

(A) Sequential DIC and fluorescence images during spore germination. The scale bar in (A) is 5 μm. (B) DIC and fluorescence image intensities as a function of germination time. The arrows indicate the times of T1, Trelease and Tlysis. DIC image intensities were calculated by normalizing a spore’s DIC image intensity to its initial value at the first time of measurement (corresponding to that of the dormant spore) after subtraction of the last unchanged image intensity value (corresponding to that of the fully germinated spore). The fluorescence image intensities were normalized to the maximum intensity value. All intensities are given in arbitrary units (a.u.).