Phylogenetic tree of <i>Thermococcales</i> based on 16S rRNA gene sequences.

<p>The evolutionary history was inferred by using the Maximum Likelihood method based on the Tamura-Nei model. The bootstrap consensus tree inferred from 100 replicates. A discrete Gamma distribution was used to model evolutionary rate differences among sites (4 categories (+<i>G</i>, parameter = 0.1068)). The rate variation model allowed for some sites to be evolutionarily invariable ([+<i>I</i>], 75.0448% sites). The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. The analysis involved 45 nucleotide sequences. All positions with less than 95% site coverage were eliminated. That is, fewer than 5% alignment gaps, missing data, and ambiguous bases were allowed at any position. There were a total of 1232 positions in the final dataset. Strains carrying sequenced plasmids are indicated by bold characters. The five plasmid-carrying <i>Thermococcus</i> strains isolated and characterized in this study are underlined.