Phylogenetic tree of genes initially identified as "Thymidylate Synthase" (TS) or "Thymidylate Synthetase" by homology searches of the non-redundant NCBI protein database. The topology and branch lengths correspond to the Maximum Likelihood (ML) inference. Bootstraps appear ordered as ML, Neighbor Joining and Maximum Parsimony. Only bootstrap values greater than 50 are shown. All of the phages are members of the Myoviridae except for siphoviruses T5, infecting E. coli, YuA, infecting Pseudomonas, and JL001, targeting a marine γ-Proteobacterium. Phage SPO1 infects B. subtilis, Felix O1 infects many species of Salmonella and wV8 infects E. coli. The rest of the phages belong to the T4 superfamily, most of them infecting E. coli and some strains of Shigella. However, KVP40 infects Vibrio parahaemolyticus, 31 infects A. salmonicida, φW-14 infects D. acidovorans, and KP15 infects Klebsiella pneumoniae. Coliphage LZ2 was isolated by Sean Eddy from the Denver zoo and several segments were sequenced in the Kutter lab, in comparison with those from a number of other T4-like phages .