FIG 4.

SarR-regulated PIA production and biofilm development in S. epidermidis. (A) Comparative immunoblot analysis of PIA production in whole-cell extracts of CSF41498 and its isogenic rbf, sarR, and rbf sarR mutants grown overnight at 37°C in BHI medium and BHI NaCl. Cell extracts were diluted 1:10, 1:100, and 1:1,000. The blot shown is representative of the results of three independent experiments. (B) CSF41498 and its isogenic rbf, sarR, and rbf sarR mutants grown in BHI and BHI NaCl in flow cells at 0.4 dyne/cm² shear using a BioFlux 1000Z instrument. The bright-field images depicting biofilm accumulation after 18 h were captured at ×10 magnification and are representative of the results of three independent experiments. (C) Comparative biofilm phenotypes of CSF41498 and its isogenic rbf, sarR, and rbf sarR mutants, complemented where indicated with pLIsarR or pEPrbf. Semiquantitative measurements of biofilm formation under static conditions were performed in tissue culture-treated 96-well plates. All the strains were grown at 37°C in BHI and BHI NaCl for 24 h. Experiments were repeated at least five times, and average results are presented. Standard errors of the mean are indicated, and the asterisks denote a significant difference as determined by Student's t test (P < 0.05).