FIG. 4.

Phylogenetic placement of tetracycline resistance genes encoding RPPs. The sequence of the Aquifex aeolicus fusA gene encoding translation elongation factor EF-G is used as the outgroup for rooting the tree. The numbers above nodes indicate the number of times that a tree configuration occurred among 1,000 bootstrap trials. Scale bar = 0.1 fixed nucleotide substitution per sequence position. The tet(M)-harboring strains isolated in this work are indicated by boldface type. These strains were not incorporated into the phylogenetic analysis and were placed in the Tet M cluster arbitrarily based on sequence similarity.