Selective colonization of microplastics, wood and glass by antimicrobial-resistant and pathogenic bacteria

Area of Science:

• Environmental microbiology
• Plastic pollution
• Antimicrobial resistance (AMR)

Background:

• The Plastisphere, microbial communities on plastic debris, may harbor pathogenic and AMR bacteria.
• Previous studies often lacked appropriate controls, limiting understanding of microplastic-specific risks for AMR pathogen spread.
• Evidence is needed to confirm if microplastics uniquely enrich and disseminate AMR bacteria.

Purpose of the Study:

• To investigate selective colonization of microplastics and natural substrates by AMR bacteria and pathogenic *Escherichia coli* (ExPECs).
• To compare AMR and ExPEC prevalence on different polymer types, sources, and morphologies against natural and inert substrates.
• To assess the impact of particle surface roughness on AMR colonization.

Main Methods:

• Utilized culture and molecular methods (quantitative polymerase chain reaction (qPCR)) to determine AMR prevalence.
• Employed multiplex colony PCR to identify extra-intestinal pathogenic *Escherichia coli* (ExPECs).
• Compared colonization on environmentally sampled microplastics (polystyrene, polyethylene), natural substrate (wood), inert substrate (glass), and controls.

Main Results:

• Polystyrene and wood particles significantly enriched AMR bacteria.
• Sewage-sourced bio-beads specifically enriched ExPECs.
• Particle roughness influenced colonization, with less smooth particles like polystyrene and wood showing higher AMR enrichment; surface weathering of polyethylene did not significantly alter AMR prevalence.

Conclusions:

• Substrate-specific traits, particularly surface roughness, enhance the colonization of both plastic and natural particles by AMR and pathogenic bacteria.
• The Plastisphere, alongside natural substrates, can act as a reservoir for AMR bacteria.
• Findings underscore the need for careful consideration of substrate properties in assessing risks of AMR spread in aquatic environments.