Enrichmed marine microbial community on plastics

Microbial communities in aquatic habitats, ranging from small freshwater streams to the vast oceans, are confronted with plastics. In marine ecosystems, these plastic particles are rapidly colonized by microorganisms, however, the exact role of microorganisms attached to plastics is not yet elucidated or has even been considered negligible. In our research, we exposed a marine microbial community to different types of plastics under laboratory conditions with variations in nutrient concentration, to enrich microorganisms with the metabolic capability to degrade those plastics. The presence of plastic induced a plastic- and nutrient-specific shift in the composition of the microbial community. To improve biofilm formation on the plastic particles and clarify the role of the plastisphere bacteria in the degradation process, a continuous trickling filter was set up. The relative abundance of the microbial community in the effluent and plastisphere evolved differently over time, depending on the plastic material supplied. After four weeks, the microbial community in the effluent of the trickling filter supplied with B4PF01 plastic already had a remarkable high abundance of the genus Alcanivorax (up to 80%), a genus well-known for oil degradation. This genus was also present in the plastisphere, but in lower abundance (up to 20%). For the PHBH trickling filters, Oceanobacter dominated both effluent and plastisphere samples. The dissolved organic carbon level in the recirculating medium indicates depolymerisation by the plastisphere microorganisms, while free-living effluent bacteria thrive on the soluble compounds.