Table 4. Membrane potential (ΔΨ), pH gradient (ΔpH) and proton motive force (Δp) quantitation in malate-grown P. denitrificans cells.
| Experimental condition | ΔΨ (mV) | ΔpH (mV) | Δp (mV) | Respiration rate (mol O2/min/mol cyt aa3) |
|---|---|---|---|---|
| No addition | -125.7 ± 3.8 | -10.5 ± 2.5 | -136.2 ± 3.1 | 83.3 ± 12.4 |
| + Malate | -154 ± 2.9 | -4.9 ± 2.3 | -158.9 ± 2.4 a | 222.8 ±12.3 |
| + KCl | -129.7 ± 3.1 | -39.3 ± 3.5 | -169.0 ± 3.0 a | 847.1 ± 22.1b |
| Hypoxia | -115.0 ± 3.4 | 9.9 ± 2.7 | -105.1 ± 3.1 | 0 ± 0 |
| Nigericin | -100.6 ± 3.4 | 1.0 ± 0.7 | -99.6 ± 3.1 | 0 ± 0 |
Mean ± SE of 10 independent determinations. Values were determined between 2 min after addition of 10 mM KCl and before oxygen was largely depleted.
aΔp was statistically different between the + Malate and the + KCl conditions (p = 0.0003) according to a paired t-test.
bMaximal rate determined >2 min after addition of 10 mM KCl. Respiration rate within 1 min after KCl addition was 676.8 ± 23.2 mol O2/min/mol cyt aa3.