Fig. 2

Phylogeny of full-length endo-chitinase encoding genes from cultivated bacteria. The evolutionary history was inferred using the Maximum Likelihood method based on the Generalized Time Reversible model (GTR). The tree with the highest log likelihood (−69520.19) is shown. A discrete Gamma distribution was used to model evolutionary rate differences among sites (5 categories (+G, parameter = 5.2345)). The tree is drawn to scale, with branch lengths measured in the number of nucleotide substitutions per site. The percentage (≥ 70%) of trees in which the associated taxa clustered together is shown next to the tree nodes (1000 bootstrap repetitions), with solid and open circles representing ≥ 90% and between 70 and 89% bootstrap support, respectively. Codon positions included were 1st + 2nd + 3rd + noncoding, and a partial deletion model with 85% site coverage was employed in tree construction. The analysis involved 90 nucleotide sequences mostly retrieved from fully sequenced bacterial genomes (n = 85), including the 19 genomes examined in detail in this study (Fig. 1, Table 1), and span 16 bacterial genera across four phyla. There were a total of 1189 positions in the final dataset. Coding sequences containing GH18 (n = 69) and/or GH19 (n = 10) domains (endo-chitinases—EC 3.2.1.14), as revealed by Pfam annotations, are highlighted with blue and red dots next to tree labels, respectively. Eleven further sequences have been included for which neither GH18 nor GH19 domains could be identified using Pfam-based annotations, but which showed significant levels of homology with endo-chitinase sequences present in NCBI’s protein database. Other domains annotated within the analyzed coding sequences were as well labeled with colored dots and are identified on the right panel next to the tree. Trans-membrane and signal peptide domains could be annotated for nearly all analyzed coding sequences. For further details on the distribution of protein domains across all sequences and the closest phylogenetic relative to each sequence query, see Additional file 1: Table S4