Metabolomic analysis of plastisphere microbial communities in the river-sea continuum

Studies of the microorganisms that live on plastic waste (the plastisphere) have revealed an original ecosystem that is arousing growing interest in the context of plastic pollution. This study presents the first non-targeted metabolomic analysis of the plastisphere, in order to better characterize the metabolic activities of the microorganisms that thrive there. This work was carried out as part of the Tara Microplastics expedition, where polyethylene pellets were immersed for a month in five sampling stations along the river-sea continuum of nine of Europe's major rivers. Liquid chromatography techniques coupled to high-resolution mass spectrometry were used to analyze the metabolic extracts of the microbial biofilms. The results revealed a clear distinction between freshwater and seawater plastisphere metabolomes. For the Loire, Rhône, Seine and Thames, the intensities of a large number of variables correlated with the salinity gradient. Metabolomes appear similar in the Rhine and Rhone, while differing from the Tiber and Loire, which showed greater similarity with the Thames and Seine. Putative annotations of 189 discriminating metabolites suggest that lipid metabolism was significantly modulated. These results confirm the significant influence of environmental factors on the diversity and functions of microorganisms living on plastic debris. This work shows that the metabolomics approach is a promising tool for refining our understanding of the functioning of the complex plastisphere ecosystem. Also see: https://micro2024.sciencesconf.org/558620/document