Fig 8.

Influence of external pH and salt on swimming speed of a V. cholerae ΔpomAB strain producing PomAB. The swimming speed of single cells was determined by recording their movement. A minimum of 200 tracks of individual cells was analyzed for each condition of pH and salt. Only bacteria exhibiting a swimming speed of ≥4 μm s⁻¹ were included in the analysis, and these represent 100% of the motile cells under the indicated condition. Data points represent the fraction of fast-swimming cells exhibiting motilities between 18 and 30 μm s⁻¹ as a percentage of the total number of motile cells at the indicated condition. ▼, 11 mM Na⁺ and 170 mM NaCl; ▲, 11 mM Na⁺ and 170 mM KCl; •, 11 mM Na⁺.