FIG. 1.

Neighbor-joining tree (22) showing relationships of partial 16S rDNA sequences from soil communities with reference AAO sequences and those of other selected β-proteobacteria. The scale equals 10% estimated substitutions calculated by the Kimura correction (9). Bootstrap values represent percentages from 100 parsimony–maximum-likelihood analyses (29). Cloned sequences from native and tilled soils are designated KZOO_D and KZOO_H, respectively. Abbreviations representing other AAO sequences are as previously described (27).