Phylogenetic tree of T7-like primase/helicase sequences amplified from sewage samples with degenerate primers designed with PhiSiGns. The eight core T7-like phages and three cyanophage P60-like phages are shown in red and green, respectively. The sewage sequences amplified in this study are shown in blue. The SEWAGE clade represents the compressed view of 49 closely related sequences recovered from sewage in this study. Internal nodes with bootstrap support ≥ 70% are shown with the corresponding bootstrap value indicated. The scale bar represents the number of nucleotide substitutions per site.