Fig. 2

Phylogenetic tree showing the position of CM1 relative to type strains of other Methanosarcina species. The strains and their corresponding accession numbers are shown. The evolutionary history was inferred using the Neighbor-Joining method [45] with Methanobrevibacter ruminantium used as an outgroup. The optimal tree with the sum of branch length = 0.43777587 is shown. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) are shown next to the branches [46]. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the Kimura 2-parameter method [47] and are in the units of the number of base substitutions per site. The rate variation among sites was modeled with a gamma distribution (shape parameter = 1). The analysis involved 13 nucleotide sequences. All positions containing gaps and missing data were eliminated. There were a total of 1081 positions in the final dataset. Evolutionary analyses were conducted in MEGA5 [48]