Fig. 2

Biofilm phenotypes of the bcsZ deletion mutant of S. Typhimurium UMR1. a Rdar morphotype formation and b Calcofluor (CF) binding of S. Typhimurium UMR1 wildtype (WT) is enhanced upon deletion of bcsZ. Interestingly, overexpression of BcsZ did not complement the phenotype. c Calcofluor staining of colonies grown on agar plates indicates higher cellulose production in the bcsZ mutant. Overexpression of BcsZ complemented the phenotype, while overexpression of the catalytic mutant BcsZ_E56A showed a more patchy distribution of Calcofluor staining. d Expression of the biofilm regulator CsgD and the subunit of curli fimbriae CsgA is not altered upon deletion of bcsZ. e Cell clumping and biofilm formation of S. Typhimurium WT 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. a, c, d, e: S. Typhimurium WT and derivatives were grown on LB without salt agar plates for 48 h at 28 °C. B: S. Typhimurium WT and derivatives were grown on LB without salt agar plates for 16 h at 28 °C. f Pellicle strength of S. Typhimurium in standing culture is enhanced upon deletion of bcsZ. S. Typhimurium WT and derivatives were grown in LB without salt standing culture for 48 h at 28 °C. Shown is a representative experiment with n = 24 for WT-VC and ΔbcsZ-VC and n = 6 technical replicates for the other derivatives. Error bar indicates SD. ***p < 0.0005, **p<0.001, *p < 0.05; ns not significant using Student’s paired t-test. Sample order remains for a–c (as shown on the left panel) and d–e (as shown on the top panel). VC pBAD30; pBcsZ BcsZ cloned in pBAD30; pBcsZ _E56A BcsZ catalytic mutant cloned in pBAD30. ΔcsgD-VC and ΔbcsA-VC serves as negative controls for d and e respectively