FIG. 4.

Phylogenetic tree showing the distributions of the OTUs related to sulfur-oxidizing bacteria, which were obtained from 42-day-old (uncorroded, NC), 102-day-old (slightly corroded, SC), and 1-year-old (heavily corroded, HC) samples. The tree was generated by using approximately 1,400 bp of the 16S rRNA genes and the neighbor-joining method. The scale bar represents 2% sequence divergence. The values at the nodes are bootstrap values (500 resampling analysis). The Aquifex pyrophilus sequence served as the outgroup for rooting the tree. The numbers in parentheses indicate the frequencies of appearance of identical clones in the clones analyzed.