FIGURE 3.

Taxonomic assignments of 16S rRNA gene sequences of enrichment cultures in (A,C) the NH₄Cl-fed bioreactor and (B,D) NaNO₂-fed bioreactor. (A,B) Relative abundances of taxonomic groups were analyzed at the family classification level. Unassigned taxon and phylogenetic groups occupying <3% of the total bacteria in all samples were integrated to “unassigned or rare groups.” (C,D) Relative abundances of taxonomic groups in the family Nitrospiraceae were analyzed at the OTU level. OTUs occupying <2% of the total bacteria in all samples were integrated into “rare OTUs.”