Neighbour-joining phylogenetic tree showing the relationships of the 201 sequences of bacterial <i>amoA</i> genes detected in the clone libraries constructed from samples from the soil column with their most similar sequences and the sequences of known AOB.

<p>The numbers at the nodes are percentages that indicate the levels of bootstrap support from 1000 replicates. The scale bar represents 0.05 nucleic acid substitutions per nucleotide position.