FIG. 4.

Unrooted tree showing the phylogenetic relationships of Thiomicrospira strains present in the highest MPN dilutions containing Thiomicrospira cells. The tree is based on partial 16S rRNA sequences and was produced by using the neighbor-joining algorithm with maximum-likelihood correction. The sequences determined in this study are indicated as follows: Tms-MPN/x-y mm depth, where x-y mm depth indicates the depth of the sediment from which a sequence was obtained. The sequence of Chromatium vinosum was used as an outgroup. The numbers on the branches are bootstrap values (1,000 replicates); only values greater than 50% are shown.