Fig. 3.

Biofilm phenotypes of the bcsZ deletion mutant of curli deficient S. Typhimurium derivatives of UMR1. a Pdar morphotype formation indicative for the expression of cellulose and b Calcoflour binding of S. Typhimurium UMR1ΔcsgBA is enhanced upon deletion of bcsZ, but could be complemented by overexpression of BcsZ. c Calcofluor staining of cells resuspended from colonies grown on agar plates indicate higher cellulose production in the bcsZ mutant. Overexpression of BcsZ complemented the phenotype, while overexpression of the catalytic mutant BcsZ_E56A showed a patchy distribution of Calcofluor staining. d CsgD expression is not altered upon deletion and overexpression of bcsZ. e Cell clumping and biofilm formation of S. Typhimurium UMR1 ΔcsgBA is enhanced upon deletion of bcsZ upon growth in M9 minimal medium for 16 h. Overexpression of BcsZ, but not of the catalytic mutant BcsZ_E56A complemented the phenotype. f Biofilm formation of UMR1 ΔcsgBA and derivatives in microfluidic chambers. Enhanced biofilm formation was not complemented by BcsZ overexpression, and further enhanced by overexpression of the catalytic mutant BcsZ_E56A. Sample order remains for a–e as shown on the top panel. VC pBAD30; pBcsZ BcsZ cloned in pBAD30; pBcsZ _E56A BcsZ catalytic mutant cloned in pBAD30