Shells regular 0.8 to 1.1 microns in diameter, isolated or in pairs, but the presence of non-mobile pili. Strict anaerobes tolerant of low oxygen levels (up 2%). Chemo-heterotrophic organotrophic using starch, glycogen, gelatin, beef extract, yeast extract and peptone. Produce acetate, propionate, isobutyrate, butyrate, isovalerate, H2 and CO2. Growth is stimulated in the presence of sulfur is reduced to H2S. Conditions of high temperatures (70-78 ° C) and acidity (pH 3.5 to 4.5) are required for growth. Resistant to chloramphenicol, kanamycin, oleandomycin, streptomycin and vancomycin. Susceptible to erythromycin, novobiocin and rifampicin. DNA: 31 mol% G+ C. One species isolated from a hot spring in the Philippines, Caldisphaera lagunensis .
