Effect of polymer type on the colonization of plastic pellets by marine bacteria

Plastic is omnipresent in the oceans and serves as surface for biofilm-forming microorganisms. Plastic debris comprises different polymers, which may influence microbial colonization and here, we evaluated if polymer type affects bacterial biofilm formation. Quantifying the biofilm on polyethylene (PE), polypropylene (PP) or polystyrene (PS) pellets by six marine bacterial strains (Vibrio, Pseudoalteromonas, Phaeobacter) demonstrated that each strain had a unique colonization behavior with either a preference for PS or PP over the other polymer types or no preference for a specific plastic type. PE, PP, and PS pellets were exposed to natural seawater microbiota using free-living or total communities as inoculum. Microbial assembly as determined by 16S rRNA (V4) amplicon sequencing was affected by the composition of the initial inoculum and also by the plastic type. Known polymer and hydrocarbon degraders such as Paraglaciecola, Oleibacter, and Hydrogenophaga were found in the plastic biofilms. Thus, on a community level, bacterial colonization on plastic is influenced by the microorganisms as well as the polymer type, and also individual strains can demonstrate polymer-specific colonization.