The Invisible Threats of Sunscreen as a Plastic Co-Pollutant: Impact of a Common Organic Uv Filter on Biofilm Formation and Metabolic Function in the Nascent Marine Plastisphere

Abstract

Plastic debris in marine environments serves as a substrate for microbial colonization, forming biofilms known as the plastisphere. Also accumulating on plastic debris are co-pollutants, including UV-protective organic UV-filters, which likely interact with this niche due to their lipophilicity. While plastispheres have been studied for their ecological and bioremediative roles, the effects of chemical co-pollutants on these communities remain poorly understood. This study investigates the impact of organic UV-filter co-pollution on the composition and function of marine microbial communities. To do so, low-density polyethylene (LDPE) was incubated with marine microbial communities for six days to cultivate a nascent plastisphere, which was then exposed to EthylHexyl MethoxyCinnamate (EHMC), a common organic UV-filter in sunscreens. Metagenomic analyses revealed that EHMC favoured the growth of bacterial generalists, such as Pseudomonas and Psychromonas, while reducing hydrocarbonoclastic genera like Marinomonas. Analysis of 3890 proteins revealed consistent upregulation of biofilm-related proteins in Pseudomonas, including outer membrane porin F (OprF), which regulates exopolymeric substance (EPS) production. Additionally, proteins indicative of a shift from aerobic to anaerobic respiration were expressed after EHMC exposure, contributing to changes in community composition. These findings highlight the need to consider chemical co-pollutants in plastisphere research.

Keywords: Plastic, Co-pollution, UV filter, Marine biofilm, Plastisphere