Simultaneous DIC image intensities and Raman spectra of single optically trapped B. subtilis spores germinating with berberine.
(A, C) Time-lapse Raman spectra of two individual spores germinating at 37°C with 10 mM L-valine and 35 μg/mL berberine in 25 mM K-HEPES buffer. (B, D) Intensities of CaDPA and berberine-specific Raman bands at 1,017 cm-1 and 1,518 cm-1 and DIC image intensity as a function of germination time. The black arrows indicate the times of T1, Trelease and Tlysis. The DIC image intensities were normalized 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). CaDPA-band intensities at 1,017 cm-1 were normalized to the initial values at the first time of measurement, and berberine-band intensities at 1,518 cm-1 were normalized to the maximum intensity value, as described in Methods.