FIG 1.

Comparison of WT and Arc mutant GAS during planktonic and biofilm growth. (A) Number of CFU/ml of the WT and arc mutant strains at indicated time points after inoculation of a planktonic culture in THY-B both with and without supplementation with 10 mM l-arginine. (B) Representative cross sections of WT and arc mutant biofilms formed on unbuffered THY-A after 144 h. The white bar represents 100 μm. (C) Maximum biofilm thickness measured as outlined in Materials and Methods using either COMSTAT2 or ImageJ to analyze images obtained by confocal microscopy at the indicated time points. (D to F) Number of CFU/ml of the WT and arc^– mutant strains at indicate time points after inoculation of a biofilm culture on THY-A plates with and without supplementation with 10 mM l-arginine. (D) Unbuffered THY-A with and without supplementation with 10 mM l-arginine. (E) THY-A buffered at pH 7.5. (F) THY-A buffered at pH 6.5 with and without supplementation with 10 mM l-arginine. Data presented represent the means ± standard deviations (SD). *, P < 0.05; **, P < 0.01; ***, P < 0.001.