FIG 4.

Confocal microscopy analysis of biofilms of KT2440 harboring both an lapA::mCherry and an lapF::gfp fusion. Biofilms were observed after 6 h (A, B, and C) or 24 h (D, E, and F) of growth. Fluorescence and pseudo-Nomarski images were combined to detect cells expressing lapA (A and D), lapF (B and E), or both (C and F). Scale bar, 20 μm. In panel F, output from the red channel was increased to correct for the higher fluorescence of the lapF fusion at this time. Insets are close-ups to show heterogeneity at the individual cell level more clearly. The arrow in the panel C inset points to an example of high lapA expression at 6 h.