TABLE 1.

Correlation between cell speed and PF stiffness in wild type and the mutants

StrainSwarm diam (mm)aMean speed (μm/s) ± SDRelative speedbHelix (mean μm ± SEM)Modulusc
PitchDiamRBMRTM
Wild type14.040.0 ± 4.01.002.84 ± 0.10.86 ± 0.061.001.00
flaB3 mutant12.035.0 ± 2.50.872.78 ± 0.10.74 ± 0.080.931.24
flaA mutant9.029.0 ± 3.00.722.40 ± 0.20.59 ± 0.060.760.62
flaB1 mutant9.029.0 ± 3.50.722.70 ± 0.10.75 ± 0.040.811.02
flaB2 mutant6.025.0 ± 4.50.622.70 ± 0.20.69 ± 0.060.871.16
flaA flaB3 mutant9.020.0 ± 2.50.501.92 ± 0.10.44 ± 0.060.690.86
flaA flaB1 mutant2.517.0 ± 2.00.421.77 ± 0.20.35 ± 0.050.570.64
flaA flaB2 mutant2.516.0 ± 2.50.401.80 ± 0.10.38 ± 0.060.630.78
flaB1 flaB3 mutant7.521.0 ± 2.50.522.70 ± 0.20.84 ± 0.07NANA
flaB1 flaB2 mutant00000NANA
  • a The data are expressed as the swarm diameter of a given mutant after subtracting that of the nonmotile flaB1 flaB2 mutant.

  • b Except for the flaB1 flaB3 mutant, the strains were ordered based on their decreasing relative speed. The relative speed is the mean swimming speed of the mutant bacteria divided by the mean swimming speed of the wild-type cells.

  • c The relative bending modulus (RBM) and the relative twist modulus (RTM) are the stiffness of the flagellum to bending and twisting, respectively, divided by the bending or twisting modulus of the wild-type flagellum. NA, not applicable.