FIGURE 2.

16S rRNA gene sequence based family tree of the phylum Actinobacteria depicting the genera with known quorum sensing systems. The evolutionary history was inferred using the Neighbor–Joining method (Saitou and Nei, 1987) using the bootstrap test of phylogeny (1000 replicates) (Felsenstein, 1985). The evolutionary distances were computed using the Kimura 2-parameter method (Kimura, 1980) Evolutionary analyses were conducted in MEGA6 (Tamura et al., 2013). A total of 54 sequences were used for constructing the tree and belonged to the type species of the type genera of each family as described in Ludwig et al. (2012) and are submitted as Supplementary Data in fasta format. Black color branch denotes family with no evidence of quorum sensing; red color denotes family with experimental evidence of quorum sensing; green color denotes family for which only gene homologs are known; ‘^∗’ indicates genus for which only gene homologs are known; and ‘^∗∗’ denotes genus for which putative AHL-like signal molecules are involved in quorum sensing.