Table 1.

Characteristics of 24067 parent and variant isolates

IsolateColony morphologyMelanin productionDoubling time (h)aCapsule size (μm)bCell diam (μm)cO -Acetyl contentdZeta potentiale
ParentSmoothYes3.42.39 ± 0.739.46 ± 1.71:3 −25.8 ± 0.20
VariantSmoothYes3.42.03 ± 0.4210.0 ± 1.41:11−25.7 ± 0.21
  • a Calculated by plotting CFU/milliliter versus time for parent and variant cells over 38 h and using the curve fitting program of the SigmaPlot (Jandel Scientific) graphing software.

  • b Measured from cell wall to outer border; mean ± standard deviation of 28 measurements; P for capsule size comparison = 0.028 (Student t test).

  • c Measured from one edge of capsule to opposite edge; mean ± standard deviation of 28 measurements; P for cell diameter = 0.2. (Student t test).

  • d Determined by NMR; reported as ratio of the number of O -acetyl groups to the number of mannose residues.

  • e P for comparison of parent and variant zeta potential = 0.234 (Student t test).