| Affiliation: | (1) Department of Earth and Planetary Sciences, University of California Berkeley, McCone Hall, Berkeley, CA 94720-4767, USA;(2) Chemistry Department, University of Wisconsin Madison, 1101 University Avenue, Madison, WI 53706-1396, USA;(3) Department of Food Microbiology and Toxicology, University of Wisconsin Madison, 1925 Willow Drive, Madison, WI 53706-1692, USA;(4) Geology Department, Carleton College, One North College Street, Northfield, MN 55057, USA;(5) Department of Environmental Science, Policy and Management, University of California Berkeley, 369 McCone Hall, Berkeley, CA 94720-4767, USA;(6) Present address: Geology Department, Carleton College, One North College Street, Northfield, MN 55057, USA |
| Abstract: | Ferroplasma acidarmanus thrives in hot, extremely low pH, metal-rich solutions associated with dissolving metal sulfide ore deposits. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and thin layer chromatography analyses of F. acidarmanus membranes indicate that tetraether lipids predominate, with at least three core lipid structures. NMR measurements indicate that the cytoplasmic pH of F. acidarmanus is ~5.6. The optimal growth pH is ~1.2, and the lowest growth pH is ~0.0. Thus, these organisms maintain pH gradients across their membranes that approach 5 pH units. Tetraether lipids were originally thought to be specifically associated with thermophiles but are now known to be widely distributed within the archaeal domain. Our data, in combination with recently published results for thermophilic and mesothermophilic acidophilic archaea, indicate that there may be a stronger association between tetraether lipids and tolerance to acid and/or large metal ion gradients. |
