Bacterial communities and related resistomes on microplastic and other organic particles of natural origin are similar to each other but differ from those free-living in the waters of the Tyrrhenian Sea

In this study, we sampled the Tyrrhenian Sea, selecting two coastal sites, with a different degree of anthropogenic pollution, and a pelagic site to assess the current coastal influence on open water. At each site, we collected water samples and isolated, quantified, and identified microplastic particles (MPs), as well as natural organic particles (NOPs). We analyzed the planktonic bacterial community and assessed the biofilms developed on both MPs and NOPs by shotgun metagenomics. Using the same approach, we characterized the antimicrobial resistome (total content of antimicrobial resistant genes, ARGs) of the planktonic community and within the sessile community of MPs and NOPs. Additionally, we reconstructed metagenome-assembled genomes from water, MPs, and NOPs, unveiling the potential hosts for the ARGs.