Fig. 2.

Unrooted phylogenetic trees of the 86 group I AoxB sequences (152 unambiguously aligned positions). The 86 sequences were retrieved from the nonredundant database of the NCBI, deduced from aoxB genes from 4 isolated strains (in bold and underlined) or deduced from the 24 PCR products obtained from metagenomic DNA (in red). Phylogenetic analyses were performed using the maximum likelihood approach implemented in Treefinder (19). The LG + Γ4 model was used for this purpose, as suggested by the “propose model” tool available in Treefinder. Numbers at branches are bootstrap values determined using the nonparametric bootstrap approach implemented in Treefinder (based on 100 replicates of the original data set). The scale bar represents the average number of substitutions estimated per site.