3.1 HI1A and P1 plasmids transfer to the sewage community
To investigate the transfer dynamics of the HI1A plasmid R27 across the
selected sewage communities, we inserted the gfp tag into the
Tn10 tetracycline resistance region (supplementary figure 4), resulting
in its deletion. Performing conjugation assays, we introduced the donor
strain, E. coli MG1655, carrying R27 into sewage communities from
three Swedish urban area WWTPs (Ellinge-, Klagshamn-, and
Sjölunda-WWTP). In parallel, we performed analogous matings with the
IncP1 plasmid, pB10, as a benchmark for broad host range transfer
(figure 2a).
We consistently observed plasmid transfer ranging from 2.6 x
10-5 to 2.8 x 10-4 T/R for R27 while
the transfer of pB10 ranged from 2.6 x 10-2 to 3.2 x
10-1 T/R in all three sewage communities. This
corresponds to an average ~1150-fold lower transfer of
R27 than pB10 (p<0.001) (figure 2a).