Using the list of 37 bacterial Phyla catalogued on LPSN as at 26 Feb 2021 [50], we systematically determined whether BamA, TamA, TamB, and TolC homologues were encoded within each Phyla (green circles) or are absent (empty). Data underlying this figure are either (i) presented in Fig 4A and S1 Data (for TolC); (ii) presented in S7 Fig (including accession IDs where relevant); or (iii) has otherwise been published previously [20,28]. Due to the unusual characteristics of the Actinobacteria and Firmicutes, we have separately listed the Orders and Class with divergent membrane profiles in parentheses below their respective Phyla. For the Thermomicrobia, we have separately listed the number of validly published species with the indicated membrane profiles. LPS, lipopolysaccharide; OM, outer membrane; PGN, peptidoglycan.