Shells regular to irregular, 1-2 microns in diameter, single or in pairs, Gram-negative, non-motile, wall type S monolayer attached to the cytoplasmic membrane. Barophiles and hyperthermophilic acidophilic heterotrophic. Electron acceptor: sulfur fermentation substrates: starch, yeast extracts, beef extract, soy extract, metabolite: acetate. Growth stimulated by sulfur, of yeast extract requires (0.1 g / l). Optimum growth at 85 ° C (60-92 ° C), pH 3.8 (2-6). DNA: 54 mol% G+ C. One species isolated from a hot spring of Kamchatka acid, Acidilobus aceticus .
