ThT Accumulation Is due to the Negative Surface Potential of Spores
(A) ThT fluorescence images with mutant strains lacking spore coats. Microscopy images of phase contrast (upper panels) and ThT fluorescence (lower panels) of wild-type (wt), ΔsigK, and ΔgerE strains. Scale bar, 1 μm.
(B) Box and whisker plot showing peak ThT intensities in wt, ΔsigK, and ΔgerE strains. Thirty cells were analyzed for each strain from two independent experiments. The boxes and whiskers show IQR (interquartile range) and 1.5x IQR, respectively.
(C) Histogram of ThT intensities on endospores with wt, ΔcotU, ΔcotC, ΔcotB, ΔcotBG, and ΔgerE. The number of endospores analyzed from at least two independent experiments is indicated in each panel. Histogram of wt strain is shown in gray in all panels for comparison with mutant strains (shown in orange). ΔcotBG and ΔgerE strains exhibit 13.5% and 43% reduction of average ThT intensity levels from wt.