Phylogenetic relationships of planctomycetes. A maximum likelihood (PhyML) tree based on 16S sequences of Planctomycetes. An outgroup consisting of reference sequences from the Verrucomicrobia were used for tree calculation, but is not displayed in the tree. Bold letters designate sequences derived from the present study, which include one representative of each OTU and the P1 isolate. Reference sequences from the SILVA database are described by their GenBank accession numbers, origin of the sequence (environmental or cultured strain) and the habitat they were obtained from. The vertical lines mark phylogenetic lineages of interest. The percentage of each clone library that was made up of sequences from each phylogenetic lineage is indicated. Bootstrap values >60 (based on 1000 bootstraps) are displayed. The scale bar indicates 0.10 (10%) sequence divergence.