Fig. 4

Phylogenetic tree of Methylocella-specific mmoX clones and operational taxonomical units (OTUs) retrieved by amplicon sequencing from various environmental DNA samples. Methylocella-specific mmoX clones and OTUs are grouped either around Methylocella tundrae T4 (red circles), Methylocella silvestris BL2 (green circles), Methylocella palustris K (blue circles) or distantly (black circles) from any known Methylocella strains (solid symbols). Environments where a particular OTU is abundant are shown in brackets. Partial mmoX sequences of representative clones and OTUs (abundance higher than 1%) and mmoX sequences from characterised methanotrophic bacterial strains were aligned using Mega 7.0. The optimal tree with the sum of branch length = 2.98 is shown where the evolutionary history was inferred using the neighbour-joining method taking into account a total of 323 nucleotide positions in the final dataset. The percentage (greater than 50%) of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) are shown next to the branches. Scale bar represents 0.05 substitutions per site