(a) Genome statistics for newly sequenced genomes, determined by IMG/ER. Gene IDs refer to IMG bioproject or RefSeq Accession. Genomes from Almeida et. al. do not yet have accession numbers. (b) Pairwise species comparison summary total. Protein coding sequences (column ‘Shared CDS’) and nucleotides (in base-pairs - column ‘Shared nt’) determined to be horizontally transferred for every pair of species that were compared by the HGT detection pipeline. Also shows calculated ANI and 16S similarity in % (column ssu - see Materials and methods for method of determining 16S similarity). Species pairs that have ANI > 0.89 were not compared and are not shown. (c) HGT identification parameters. Different parameters for minimum length of gene match for HGT, maximum % ANI identity for related species, and maximum distance between genes in an island were compared. Number of positive HGT hits identified when varying the minimum protein coding gene length. Number of HGT groups constructed when varying the maximum separation between hits that are classified as belonging to the same group. Number of nucleotides or number of protein coding sequences in HGT regions by 16S similarity. Note - There are no results below 500 as 500 bp is the minimum length for protein coding sequences in this analysis. (d) Full group annotations. All protein coding sequences identified as HGT, sorted by group # (ranked by total nucleotide content), species and genome location within species. Certain functional annotations are identified by color (e.g. orange for iron) based on text in annotation. Locus tags and contig IDs beginning with lower case letters were assigned by kvasir, and do not correspond to any published database. (e) Group summary statistics. Summary statistics for each HGT group. (f) Highly conserved genes in Brevibacterium species. Protein coding sequences from Group 29, as well as selected highly conserved genes from Brevibacterium antiquum CNRZ918 were compared with other Brevibacterium strains by BLAST. B. linens 947.7 has substantially lower nucleotide identity for the four genes found in Group 29 than other B. linens strains, despite similar nt distance for other highly conserved genes. This suggests that Group 29 is a true example of HGT between CNRZ918 and other B. linens strains, rather than a false positive. (g) RUSTI gene expression during competition. Gene expression data from RNA seq analysis for genes in JB182 RUSTI. Related to Figure 3B (h) TCBD hits for transporters in RUSTI. Representative CDS of Actino- and ProteoRUSTI from G. arilaitensis JB182 and V. casei JB196, respectively, were compared with the Transporter Classification Database (TCDB). (i) RefSeq BLAST Actino- and ProteoRUSTI from G. arilaitensis JB182 and V. casei JB196, respectively, as well as the consensus sequence for StaphRUSTI (see Figures 3 and 4) were compared with the NCBI RefSeq database using BLAST.