Shells regular irregular, 1.5 microns in diameter, isolated or in pairs, by twenty mobility flagella at one point, Gram negative. Lysed by 2% SDS. Colony round, 1 mm in diameter, convex, smooth, yellowish. Substrates used: H2 + CO2, formate. Optimum growth at 65 ° C (30-70 ° C), pH 7 (6-8) and NaCl 40 g / l (13 to 83 g / l). Division time, 55 min. DNA: 31 mol% G+ C. Two species Methanothermococcus thermolithotrophicus isolated from marine sediments of the Bay of Naples.
