The RAPD profiles of the isolates were significantly different from those of the 22 reference strains, except for the profiles of Brest isolates 10, 12, and 13 (group G8), which were very similar to the profile of Thermococcus hydrothermalis (Pearson coefficient, >70%), and for the group G1 profiles, which shared bands with the profile of Thermococcus chitonophagus.