The two strains were sampled during the DIVA 2 cruise in 1994 (7). M. camini DV1155 was isolated from a black smoker chimney at the Menez Gwen site. This hydrothermal field is located on the Mid-Atlantic Ridge at a depth of 840 to 870 m (8). M. camini DV1197 was isolated from a colonization module deployed at the Lucky strike hydrothermal vent field. This site is located at 1700 m of depth in the Mid-Atlantic Ridge (8). Strains DV1197 and DV1155 grow optimally at 60°C and 65°C, respectively, at atmospheric pressure in a modified Ravot medium (9) with elemental sulfur instead of cysteine.