Original large DBs.

DBs were assembled based on taxonomy as assigned at NCBI, aiming for roughly even distribution of all genomes collected. After assignment to GTDB r202 species, small numbers of genomes were found to be improperly treated by placement in a different large DB than the bulk of the species’ genomes; these improperly placed genomes were excluded from further analysis and are not counted in the Species or Genomes columns. The two DBs limited to genus (Salmonella and Campylobacter) were not treated further because taxonomic outreach could not be studied, leaving 11 DBs studied herein, with totals at bottom. For these 11 DBs, the genomes treated and species composition are reported in S1 and S2 Files in S1 Data, respectively.