Vibrio Colonization Is Highly Dynamic in Early Microplastic-Associated Biofilms as Well as on Field-Collected Microplastics

Abstract

Microplastics are ubiquitous in aquatic ecosystems and provide a habitat for biofilm-forming bacteria. The genus <i>Vibrio</i>, which includes potential pathogens, was detected irregularly on microplastics. Since then, the potential of microplastics to enrich (and serve as a vector for) <i>Vibrio</i> has been widely discussed. We investigated <i>Vibrio</i> abundance and operational taxonomic unit (OTU) composition on polyethylene and polystyrene within the first 10 h of colonization during an in situ incubation experiment, along with those found on particles collected from the Baltic Sea. We used 16S rRNA gene amplicon sequencing and co-occurrence networks to elaborate the role of <i>Vibrio</i> within biofilms. Colonization of plastics with <i>Vibrio</i> was detectable after one hour of incubation; however, <i>Vibrio</i> numbers and composition were very dynamic, with a more stable population at the site with highest nutrients and lowest salinity. Likewise, <i>Vibrio</i> abundances on field-collected particles were variable but correlated with proximity to major cities. <i>Vibrio</i> was poorly connected within biofilm networks. Taken together, this indicates that <i>Vibrio</i> is an early colonizer of plastics, but that the process is undirected and independent of the specific surface. Still, higher nutrients could enhance a faster establishment of <i>Vibrio</i> populations. These parameters should be considered when planning studies investigating <i>Vibrio</i> on microplastics.