Figure 1.

Phylogenetic tree highlighting the position of S. acidophilus relative to the type strains of the other species within the genus Sulfobacillus. The tree was inferred from 1,422 aligned characters [12,13] of the 16S rRNA gene sequence under the maximum likelihood (ML) criterion [14]. The comparatively closely related genus Symbiobacterium [15] was included for rooting the tree. The branches are scaled in terms of the expected number of substitutions per site. Numbers adjacent to the branches, if any, are support values from 1,000 ML bootstrap replicates [16] (left) and from 1,000 maximum parsimony bootstrap replicates [17] (right) if larger than 60% (i.e., there were none). Lineages with type strain genome sequencing projects registered in GOLD [18] are labeled with one asterisk, those also listed as ‘Complete and Published’ with two asterisks [19].