Patterns of permissiveness towards broad host range plasmids in microbial communities across the urban water cycle in Europe

Antimicrobial resistance genes are often carried by plasmids, which greatly facilitates their spread into microbial communities. Therefore, microbial community permissiveness (the propensity of a community to take up plasmids) and the diversity of the permissive members of the community constitute key parameters to understand and predict the fate of resistance genes. This is especially true for communities across the urban water cycle. Indeed, patients under antibiotics treatment excrete resistant microbes, which are collected and transported via the sewage collection network to wastewater treatment plants (WWTP). When these resistant, host-associated bacteria mix with other bacteria better adapted to life in the environment, there is a risk of transfer of resistance plasmids. Here, we measured permissiveness towards three gfp-tagged model broad host range plasmids for communities at multiples points of the urban water cycle (hospital and residential sewers, influent of the WWTP, main WWTP reactor) in three European cities. Permissiveness to pKJK5 was highest and varied between 8.5 x 10-4 and 1.3 x 10-2 transfer per recipient, and that to RP4 was about one order of magnitude lower. Permissiveness to these two plasmids were correlated and was highest for the residential sewer samples. The cells that received the plasmids were sorted using flow cytometry and characterized by 16S rRNA gene amplicon sequencing. Preliminary analysis identified genera that are consistently capable of engaging in plasmid uptake at most points of the urban water cycle, highlighting their potential role as facilitators of antimicrobial resistance dissemination.