Neighbor joining tree based on 16S rRNA sequences showing the phylogenetic affiliation of Desulfotomaculum and related species divided in the subgroups of Desulfotomaculum cluster 1. D. kuznetsovii is printed in bold type. The sequences of different Thermotogales were used as outgroup, but were pruned from the tree. Closed circles represent bootstrap values between 75 and 100%. The scale bar represents 10% sequences difference.