FIG. 6.

Phylogenetic neighbor-joining tree based on a comparison of 152 bp of 16S rRNA gene sequences from AOB of the β subclass of the Proteobacteria and some other β-proteobacteria. The tree is rooted with two sequences of AOB belonging to the γ subclass of Proteobacteria. Our DGGE sequences are boldfaced. Their designations are composed of N, for nested PCR products; J2, S2, or S3, for a sampling date of July 2002, September 2002, or September 2003; A to L, w1, or w2, for the band as labeled in Fig. 4; and, at the end, either the name of the sampling station from which the sequence originated or WWin or WWout (explained in the legend to Fig. 4).