FIG. 7.

Phylogenetic distance trees of members of Desulfovibrionaceae family (A) and Desulfobulbus family (B) based on comparative analysis of partial sequences (575 bp for the Desulfovibrionaceae clone library and 1,093 bp for the Desulfobulbus clone library, respectively) of 16S rRNA gene sequences retrieved from a 52-day-old wastewater biofilm. The trees were calculated by neighbor-joining algorithm and a 50% conservation filter. Numbers in parentheses indicate the frequencies of appearance of the completely identical sequences (clones) in the total clones. The scale bar denotes 5% sequence divergence, and the values at the nodes represent bootstrap values (100 times resampling analysis). E. coli is used as the outgroup.