Table 2.

CFU and interfacial growth rates

StrainGenotypePhenotypePlate count data (CFU/cm2)aATR/FT-IR (amide II absorbance)
44 h 88 hLinear rate increased (mAU/h)Growth ratee [ln (1 + mAU)]/hDoubling timee(h)
FRD1mucA22Mucoid2.8 (0.9) × 107b7.7 (0.7) × 108b0.5 (0.95)0.06 (0.94)12
FRD2mucA22 algT18Nonmucoid2.0 × 1086.6 (1.3) × 1084.6 (0.98)0.35 (0.98)2
FRD440mucA22 algT::Tn501-33Nonmucoid2.6 (1.3) × 1084.1 (1.0) × 1085.4 (0.97)0.35 (0.98)2
FRD1131mucA22 algD::Tn501-31Nonmucoid1.7 (0.8) × 1071.0 (0.5) × 1095.0 (0.99)0.11 (0.98)6
FRD1153mucA22 algJ3Mucoid (no O-acetylation)4.6 (1.0) × 106c6.6 (1.7) × 108c3.2 (0.99)0.11 (0.98)6
  • a CFU were determined by scraping the attached cells from the germanium IRE with a Teflon policeman and saline, transferring the cells to a test tube, and vortexing with glass beads for 5 min. The cells were serially diluted in sterile saline and plated on L agar. Standard deviations of three samples are indicated in parentheses.

  • b 100% of FRD1 colonies were mucoid at 44 h; 98% of FRD1 colonies were mucoid at 88 h.

  • c 100% of FRD1153 colonies were mucoid at 44 h; 35% of FRD1153 colonies were mucoid at 88 h.

  • d Linear rates of increase were calculated from amide II absorbances between 32 and 64 h for FRD1, 8 and 32 h for FRD2 and FRD440, 40 and 52 h for FRD1131, and 60 and 88 h for FRD1153. r2 values for linear regressions are indicated in parentheses.

  • e Growth rates and doubling times were calculated between 24 and 60 h for FRD1, 4 and 16 h for FRD2 and FRD440, 16 and 52 h for FRD1131, and 40 and 88 h for FRD1153. The growth rate refers to the cells within the analysis range of the ATR-FTIR, within 1 μm of the IRE surface.