FIG 2.

Germination of multiple individual optically trapped wild-type B. subtilis spores monitored by Raman spectroscopy (b and d) and DIC microscopy (a and c). Optically trapped B. subtilis PS533 spores (wild type) were germinated at 37°C with 10 mM l-valine (a and b) or only 25 mM K-HEPES (pH 7.4) (c and d), and spore germination was monitored as described in Materials and Methods. Germination curves were determined from the loss in spore DIC image intensity or from the intensities of the CaDPA-specific Raman band at 1,017 cm⁻¹. The DIC image and Raman band intensities in arbitrary units (a.u.) were normalized to 1 based on the respective values at the first time of measurement, and DIC image intensities at the end of the experiment were set at 0. The arrows indicate the times of T₁, T_lag, and T_release for a single spore. The dashed lines indicate T₁ times of each individual spore.