FIG. 2.

Neighbor-joining tree of selected 16S rRNA gene sequences of ammonia-oxidizing betaproteobacteria of the Nitrosomonas and Nitrosospira lineages. Filled and empty circles indicate bootstrap values (100 resamplings) above 90 and 70%, respectively. The tree was rooted with Gallionella ferruginea (L07897), indicated by the arrow. The gray-filled trapezoidal branches include sequences of AOB belonging to the AOB lineage indicated at the side of each trapezoidal branch. The sequences included in the branches were used to calculate the tree. The scale bar represents 5% estimated sequence divergence. Bands in bold font were retrieved from benthic, pelagic, or epiphytic compartments, represented by “S,” “W,” and “M,” respectively, in the band code. The first part of the band code (R04) corresponds to the Border Lakes sampling campaign of the year 2004 and is followed by an abbreviation for the approach, i.e., “B” for nested approach I based on the βamo primer set or “u” for nested approach II based on the 27f-907r primer set.