Short-term exposure to positively charged polystyrene nanoparticles causes oxidative stress and membrane destruction in cyanobacteria

Abstract

Recently, there has been increasing global concerns about the ecological impact of micro- and nano-sized polystyrene particles in marine environments. However, the potential threats of polystyrene nanoparticles to primary producers in freshwater systems remain unclear. Here, we explore the metabolite profiles and signaling pathways of freshwater cyanobacterium Synechococcus elongatus in response to short-term (48 h) amino-modified polystyrene nanoparticle (PS-NH₂; 50 nm) exposure. We demonstrate that the positively charged PS-NH₂ were acutely toxic to S. elongatus with an EC₅₀ of 3.81 μg mL⁻¹. Non-targeted metabolomics analyses suggested oxidative stress and membrane destruction as the main causes of PS-NH₂ toxicity. Furthermore, disruption of glutathione metabolism and damage to membrane integrity were confirmed using two engineered strains of S. elongatus. These results provide new insights into polystyrene nanoparticles' impact on primary producers, improving the understanding of the toxic mechanisms of polystyrene nanoparticles in the freshwater primary producers.