FIG 2.

Surface stiffness of different B. subtilis biofilms. Young's modulus values were obtained for 1-day-old biofilms of the wild-type strains B. subtilis B-1 (red) and NCIB 3610 (blue) and three mutant strains of NCIB 3610 (blue). Error bars are Gaussian errors resulting from the error in the method. Photographs above the graph are images of single biofilm colonies. Scale bars, 1 mm. White arrows point to the faint single biofilm colonies of BslA and EpsA-O mutant strains. P values for these data are given in Table S2 in the supplemental material.