a, Aminoacyl tRNA synthetases were detected in many huge phages reported in this study (Supplementary Table 6). The phylogenetic subtree for glutamate-tRNA synthetase sequences from phages (red text and small triangles) that place within or close to sequences from Bacteroidetes hosts is shown as an example. Bacterial sequences from public databases are indicated by black text and those from metagenomes from which huge phage genomes were reconstructed are indicated by blue text. Coloured circles indicate the predicted phylum of the bacterial host for each phage. b, Phylogenetic tree of phage-encoded ribosomal protein S21 and the top RefSeq hits for each protein, constructed using IQTREE. Sequences from this study are indicated by red branches.