Assimilation of synthetic plastic nanoparticles by the oomycete Pythium aquatile

Abstract

The degradation of synthetic plastics in the environment proceeds through the stages of micro- and nanoparticles. Freshwater fungi and fungus-like organisms are key decomposers of organic material. The most fungi (including the fungus-like oomycetes) feed by osmotrophy, which involves the release of exoenzymes into the environment to break down complex biological polymers, followed by cellular uptake of simplified monomers. This article aims to cultivate oomycete Pythium aquatile Höhnk, 1953 in the presence of synthetic plastic nanoparticles as an only source of carbon compounds. The nanoparticles were bulk stained with water-insoluble fluorescent dye. We studied such widely used polymers as polystyrene (PS), poly(vinyl chloride), poly(methyl acrylate) (PMA) and poly(methyl methacrylate) (PMMA). This first experiment on exposure of plastic nanoparticles to oomycete hyphae showed the ability of these fungus-like organisms to capture these particles through a certain type of endocytosis. The fate of nanoplastics in the presence of P. aquatile depends on the chemical structure of the polymer. PMMA with a quaternary carbon atom is the most stable, PMA and PS containing the active α-CH atom are rapidly destroyed by oomycetes.