FIG. 4.

Neighbor-joining tree showing phylogenetic position of 16S rRNA gene clones generated from Area 2 soil prior to column packing. Sequences were inserted by parsimony into a tree containing all bacteria and archaea in the “greengenes” database (as of 3 May 2005). Abbreviations are as follows: β-proteo, Betaproteobacteria; γ-proteo, Gammaproteobacteria; δ, Deltaproteobacteria; G, Gemmatimonadetes; Bact, Bacteroidetes; Ver, Verrucomicrobia; P, Planctomycetes; W, candidate division WS3; D, candidate division DSS1; Acido, Acidobacteria; Chlorof, Chloroflexi; T, candidate division TM7. Values in parentheses indicate numbers of clones in each group. Methanobacterium subterraneum strain C2BIS was used to root the tree. The scale bar represents 10 inferred nucleotide changes per 100 nucleotides analyzed.