Black Queen evolution and trophic interactions determine plasmid survival after the disruption of conjugation network

Mobile genetic elements such as conjugative plasmids are responsible for antibiotic resistant phenotypes in many bacterial pathogens. The ability to conjugate, the presence of antibiotics and ecological interactions all have a notable role in the persistence of plasmids in bacterial populations. Here, we set out to investigate the contribution of these factors when the conjugation network was disturbed by a plasmid-dependent bacteriophage. Phage alone effectively caused the population to lose plasmids, thus rendering them susceptible to antibiotics. Leakiness of the antibiotic resistance mechanism allowing Black Queen evolution (i.e. race to the bottom) was a more significant factor over antibiotic concentration (lethal vs sub-lethal) in determining plasmid prevalence. Interestingly, plasmid loss was also prevented by protozoan predation. These results show that the outcome of attempts to re-sensitize bacterial communities by disrupting the conjugation network are highly dependent on ec...