Formation of specific bacterial assemblages on sterile polyethylene microplastic particles added to a marine aquaria system

Abstract Microplastics (MP) represent an anthropogenic surface for bacterial colonization in marine ecosystems. In order to determine if MP act as vectors of specific bacterial communities, which might include non-native and potential pathogens for the marine biota, bacterial assemblages formed on sterile polyethylene MP particles after 12 weeks of incubation in marine aquaria were characterized. These assemblages were compared to those formed at the same time on sterile sandy sediments and present in detritus and particulate and particle-free water fractions of the studied system. Scanning electron microscopy and bacterial 16S rRNA gene-based community fingerprinting indicated the development of specific bacterial biofilms on MP surfaces. Most abundant genera determined exclusively in high relative abundance on MP were Jejudonia, Roseivivax, Marinobacter, and Erythrobacter. The potential pathogenic genus Vibrio was detected in low relative abundances on microplastics in the amplicon dataset which was confirmed by quantitative PCR using a new designed Vibrio-specific primer system. Identifying the specific communities formed on MP surfaces is pivotal in order to understand the effects that these particles as well as the associated microbiota, have on the health of marine ecosystems.