FIG 3.

(A) Effect of low pH on growth on THY plates. (B) Growth kinetics of the S. mutans mutants and the parental UA159 strains in liquid medium. (C) IBSL32 with the pIBL36 or pIB184Km plasmid in liquid medium. For growth on pH 5.0 and 7.0 THY agar plates, diluted overnight cultures (10 μl) were spot dried and plates were inoculated for 48 h at 37°C in 5% CO₂. Growth kinetics was measured as described in Materials and Methods. Strains were grown in THY medium at pH 5.0, 5.5, and 7.0 (marked as black dotted, gray, and black lines, respectively). Samples are as follows: S. mutans UA159 (diamonds), IBSL16 (squares), IBSL28 (triangles), IBSL32 (circles), IBSL32/pIBL36 (pentagons), and IBSL32/pIB184Km (asterisks).