FIG. 2.

Phylogenetic tree based on deduced amino acid sequences of the amoA gene sequences of AOB. The evolutionary history was inferred using the neighbor-joining method (10). The percentage of replicate trees (those >50%) in which the associated taxa clustered together in the bootstrap test (10,000 replicates) are shown next to the branches (3). 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 JTT matrix-based method (5), and the unit of measure is the number of amino acid substitutions per site, shown by the bar. The number of sequences belonging to the OTU/total number of sequences is given in parentheses.