Dunaliella acidophila (Kalina) Masyuk — an alga with a positive membrane potential

• DOI: 10.1111/j.1469-8137.1989.tb04704.x
• Publication Date: 2006-04-28T15:56:34Z
• Authors: H. GIMMLER; U. WEIS; C. WEIS; H. KUGEL; B. TREFFNY
• Keywords: 0301 basic medicine; 03 medical and health sciences; 6. Clean water

SUMMARY The electrical membrane potential differences (Em) of the acid-resistant green alga Dunaliella acidophila and the salt-resistant Dunaliella parva were determined from the distribution of the lipophilic anion ["4C]isothiocyanate (SCN-) and the lipophilic cation [14C]tetraphenylphosphonium (TPP+) between the cells and the media. Dunaliella acidophila grown in a medium of pH 10 exhibited a positive membrane potential (inside of cell relative to outside) of about + 70 mV, whereas D. parva grown in a hypersaline medium of pH 7 6 had negative membrane potentials of about - 50 mV. De-energization of D. acidophila by anaerobiosis increased the positive membrane potential, whereas energization by light produced a less positive (relatively more negative) potential. This is in agreement with the operation of a plasma membrane H+-ATPase. The chemical basis for the positive membrane potential of D. acidophila and its importance for the extreme acid resistance of this alga are discussed, as well as its consequences for the uptake of cations and the cation content of the cells.