FIG. 4.

Contribution of the fnbA and fnbB genes to biofilm regulation in S. aureus. (A and B) Impact of a fnbAB::Tc^r mutation on biofilm regulation in the MRSA isolates BH10, BH1CC, and BH4 (A) and the MSSA isolates BH48, BH49, and BH51 (B). The strains were grown in BHI, BHI-4% NaCl, and BHI-1% glucose media at 37°C for 24 h. (C) Impact of fnbA and fnbB single and double mutations and carriage of multicopy fnbA (pFnBPA4) and fnbB (pFnBPB4) plasmids on biofilm development in the MRSA isolates BH1CC, BH10, BH3, BH4, and B30. The strains were grown in BHI medium supplemented with 1% glucose at 37°C for 24 h. Biofilm formation in tissue culture-treated 96-well plates was measured three times, and standard deviations, which were less than 20%, are indicated where appropriate. (D) Biofilm development under flow conditions by the MRSA strains BH1CC (vector control), BH1CC fnbAB::Tc^r, and BH1CC fnbAB::Tc^r (pFnBPA4) using a Biosurface Technologies flow system. Strains were grown for 24 h at 37°C in BHI broth supplemented with 1% glucose, and the flow cells were photographed after 24 h.