3.4 R27 transfers primarily to Enterobacteriaceae, and secondarily across order and phylum
Next, we analyzed the taxonomic composition of the transconjugant communities sewage community/R27 and sewage community/pB10. Every ASV was associated with the gram-negative phylogroup. In total we identified 65 ASVs, of which 63 were distributed within six families of Proteobacteria, while the remaining two were members of the Bacteroides family Flavobacteriaceae (figure 4a). Transconjugants of R27 and pB10 were found within all these seven families (figure 4a). Every ASV was, however, not shared by pB10 and R27; six ASVs were unique to pB10, while 19 were unique to R27 (supplementary figure 5). R27 was identified in a relatively high number of closely related Enterobacteriaceae(figure 4a). Quantification of the relative abundance emphasized that sewage community/R27 predominantly consist of Enterobacteriaceae ( = 77 %) (figure 3b). Other noticeable families of the sewage community/R27 were represented in considerable numbers ( = >3 %), including Aeromonadaceae ,Moraxellaceae , Shewanellaceae and Pseudomonadaceae(figure 4b, supplementary table 4). In contrast, the relative abundance of Enterobacteriaceae was rather low ( = 1.7 %) in sewage community/pB10, where the majority of ASVs belonged to the two families Aeromonadaceae ( = 49 %) and Pseudomonadaceae ( = 36 %) (figure 4b). Other families that represented = >3 % of the pB10 transconjugants were Shewanellaceae and Flavobacteriaceae (figure 4b & supplementary table 4). Lastly, we found a high degree of strain specificity in terms of plasmid uptake within similar genera for both transconjugant communities (figure 4a).