Fig. 4.
Inhibition of SpeB activity restores GAS biofilm formation. (a) Graphical representation of CV assays of biofilm-forming ability in the presence and absence of the cysteine protease inhibitor E64. While addition of E64 may reduce the biofilm capacity of the wild-type slightly, biofilm formation of the Δsrv strain is restored to comparable levels. E64 did not alter biofilm formation by the ΔspeB isogenic mutant strain, suggesting that the alteration in biofilm phenotype is due to SpeB activity. The data are means±SD of at least six replicates. (b) Single-well images of CV assays prior to solubilization in ethanol. After image capture, the CV from surface-attached cells was solubilized and the A600e values are shown. Note the increase in stained material in the Δsrv well in the presence of E64.