Table 2.

Kinetic parameters of Pi uptake in R. tropici CIAT899 and CAP45a

StrainGrowth conditionsHigh-affinity uptakeLow-affinity uptake
Km (μM Pi)Vmax (nmol of Pi/min/mg [dry wt] of cells)Km (μM Pi)Vmax (nmol of Pi/min/mg [dry wt] of cells)
CIAT899−Pi 0.45 ± 0.0186.2 ± 4.99.6 ± 1.0153.8 ± 13.6
+Pi 0.34 ± 0.020.22 ± 0.0135.7 ± 1.01.33 ± 0.01
CAP45−Pi NDb ND34.3 ± 2.7118.0 ± 7.5
+Pi NDND33.1 ± 1.30.41 ± 0.02
  • a The kinetics of Pi uptake were analyzed by using Eadie-Hofstee plots. The initial velocities in +Pi and −Pi cells were determined for the first 20 and 10 s, respectively. The values are means ± standard errors based on values from three separate experiments; each Pi concentration was replicated three times in each experiment.

  • b ND, not detected.