Fig. 4: Effect of bacillaene on the expression of curli structural and regulatory genes.

a, c Macrocolonies of E. coli W3110 harboring a csgB::lacZ (a) or csgD::lacZ (c) reporter fusion were grown on salt-free LB plates in close interaction with B. subtilis 3610 wt or its derivative pksL mutant. E. coli biomass from the interaction and distant zones -as indicated in the images- was collected and subjected to β-galactosidase activity analysis. The data are means ± standard deviations of β-galactosidase activities derived from the analysis of four independent interactions (n = 4). *P < 0.05; **P < 0.01; ns no significant difference (two-tailed unpaired t-tests). Scale bar in (a) represents 5 mm and is applicable to images in (a, c, e). b, d, f Macrocolonies of W3110 csgB::lacZ (b), csgD::lacZ (d) or rpoS::lacZ (f) grown on salt-free LB plates supplemented with X-gal in close interaction with B. subtilis 3610 wt or its derivative pksL mutant. The graph depicts color intensity values of X-gal at the interaction and distant zones of respective macrocolonies shown in the figure. The data represent means ± standard deviations of X-gal color intensity values from three independent interactions (n = 3). *P < 0.05; **P < 0.01; ***P < 0.001 (two-tailed unpaired t-tests). Scale bar in (b) represents 5 mm and is applicable to images in (b, d, f). e Cellular level of CsgD in W3110 macrocolonies interacting with B. subtilis 3610 wt or pksL mutant. E. coli biomass from the interaction and distant zones -as shown in the images- was collected and subjected to western blot analysis using specific antibodies against CsgD. The graph depicts the pixel intensity values of respective bands. For sample loading control, see Supplementary Fig. 4.