title: Transmembrane electrical potential and transmembrane pH gradient in the acidophile Thiobacillus ferro-oxidans.
abstract: Thiobacillus ferro-oxidans is capable of using the oxidation of Fe2+ by O2 at pH 2.0 as the sole source of energy for growth and CO2 fixation. The bacterium maintains an intracellular pH of 6.5 over a range of external pH from 1.0 to 8.0, as measured by [14C]acetate and [3H]methylamine distribution. The membrane potential was estimated by the distribution of the lipid-soluble cation dibenzyldimethylammonium and the anion SCN-. At pH 2.0 (the pH of growth) during Fe2+ oxidation the transmembrane pH gradient is 4.5 units with an opposing membrane potential of -10mV, giving a proton electrochemical gradient of +256mV. This gradient is actively maintained.
mesh_terms: D008725:Bis-Trimethylammonium Compounds / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials / Q000187:drug effects; D013855:Thiobacillus / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D013861:Thiocyanates / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D008725:Bis-Trimethylammonium Compounds; D013861:Thiocyanates; D014475:Uncoupling Agents