Table 2 Intracellular and extracellular NHX concentrations of IME169 (reference strain) and IMZ351 (Δmep) measured at steady state at varying pH values from aerobic N-limited chemostats in synthetic medium with glucose at a dilution rate of 0.05 h−1 and the corresponding NHX IC/EC ratios. For calculation of predicted intracellular/extracellular ratios with compartmentalization three compartments were considered: cytosol, mitochondria and vacuole. The ratios were calculated as the maxima and minima of a sensitivity analysis where the following critical variables were considered: vacuolar volumes (between 25 and 14% intracellular volume), cytosolic pH (between 6 and 7) and vacuolar pH (between 4 and 5.5). The data represent average and mean deviation of triplicates
Strain | pH | Average cell volume (mLIC/gCDW) | Biomass concentration (gCDW/Lbroth) | Intracellular NHX (mmol/LIC) | Extracellular NHX (mmol/LEC) | Measured IC/EC ratio | Predicted IC/EC equilibrium ratio range | |
|---|---|---|---|---|---|---|---|---|
Maximum | Minimum | |||||||
IME169 Uniport NH4 + | 5.0 | 2.59 ± 0.04 | 7.00 ± 0.02 | 1.74 ± 0.14 | 0.008 ± 0.001 | 219 ± 39 | 5.44 × 103 | 108 |
6.0 | 2.43 ± 0.04 | 7.45 ± 0.01 | 3.16 ± 0.16 | 0.011 0.003 | 302 ± 40 | 5.44 × 104 | 1.09 × 103 | |
7.0 | 2.62 ± 0.02 | 7.73 ± 0.03 | 3.33 ± 0.09 | 0.013 ± 0.001 | 254 ± 10 | 5.44 × 105 | 1.09 × 104 | |
IMZ351 Diffusion NH3 | 5.0 | 2.01 ± 0.08 | 6.44 ± 0.01 | 10.5 ± 0.7 | 6.99 ± 0.28 | 1.5 ± 0.1 | 2.57 | 0.05 |
6.0 | 2.00 ± 0.04 | 7.37 ± 0.04 | 10.9 ± 0.6 | 2.61 ± 0.09 | 4.2 ± 0.3 | 25.7 | 0.5 | |
7.0 | 2.31 ± 0.09 | 7.73 ± 0.01 | 7.48 ± 0.7 | 0.57 ± 0.02 | 13.2 ± 1.3 | 255 | 5 | |