FIG. 6.

Uptake and fate of choline in E. chrysanthemi. (A) Strains 3937 (OusA⁺ OusB⁺) (⧫), 5512 (OusA⁻ OusB⁺) (□), W245 (OusA⁺ OusB⁻) (▴), and W246 (OusA⁻ OusB⁻) (○) were grown in M63 with 0.3 M NaCl to mid-log phase and assayed for the uptake of [¹⁴C]choline (188 MBq mmol⁻¹) at a final substrate concentration of 50 μM. (B and C) Fate of [¹⁴C]choline supplied to E. chrysanthemi cells. Cells were grown in M63 with 0.3 M NaCl and 100 μM [¹⁴C]choline (94 MBq mmol⁻¹); they were withdrawn at the mid-log (B) or stationary (C) phase to analyze the oxidation of choline. Cells were harvested by centrifugation, washed with isotonic minimal medium, and extracted by 80% ethanol. The ethanol soluble fraction was analyzed by paper electrophoresis (2,000 V/cm). Signals corresponding to choline (□) and GB (▪) were analyzed by Instant Imager, and the radioactivity corresponding to each spot was determined by scintillation counting. The results are means of duplicate determinations; the standard error did not exceed 10%.