The widespread plastic pollution has raised social concern regarding these materials acting as vectors for pathogenic bacteria and antimicrobial resistance (AMR). To investigate the presence of potential pathogens within the plastisphere we performed in situ incubations of plastics i) in a river downstream from a wastewater treatment plant (WWTP), and ii) in a WWTP with posterior transition into the sea. The biofilms developed on plastics and control materials were analysed by metagenomics. Plastic materials –especially pre-weathered plastics– were enriched in AMR genes that confer resistance to various antibiotic classes, when compared to other materials and surrounding waters. In the river, typical genera associated with human pathogenicity (e.g., Escherichia, Salmonella, and Streptococcus) were relatively more abundant in the surrounding water samples than in biofilms, and metagenome assembled genomes (MAGs) belonging to these taxonomic families were among those containing AMR genes and virulence-related genes. Similar results were observed in the WWTP incubations though, most interestingly, the transition to marine conditions showed a drastic variation of the microbial community colonising the plastics, mainly due to the rapid flocculation and loss of the biofilms due to the high ionic strength of seawater. Overall, while plastics develop a distinct microbial community containing high relative abundance of AMR, in the long run, the microbial community in the plastisphere is strongly conditioned by its surrounding environment. Also, there is a need to distinguish between ‘real’ clinically relevant pathogenic and non-pathogenic taxa, as well as their survival over environmental transitions, before drawing conclusions that plastics are vectors for pathogens.

Primary Presenter: Joseph Christie-Oleza, University of the Balearic Islands (joseph.christie@uib.eu)

Authors:

Vinko Zadjelovic, University of Warwick  (vinko.zadjelovic@hotmail.com)

Robyn Wright, Dalhousie University  (Robyn.Wright@dal.ca)

Elizabeth Wellington, University of Warwick  (E.M.H.Wellington@warwick.ac.uk)

Joseph Christie-Oleza, University of the Balearic Islands  (joseph.christie@uib.eu)