Fig. 2

Phylogenetic tree of the protocatechuate 4,5-dioxygenase α subunits from different bacteria. A total of 86 sequences derived from Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Actinobacteria were selected to draw the phylogenetic tree, and 16 of them (numbered 1–16 and labeled with green circles) were evenly selected for the subsequent studies. The reported LigA and PmdA were labeled with red circles. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test are shown next to the branches