Abstract Nanoplastics (NPs) are an emerging global environmental concern. While extensive research has focused on the toxicological effects of NPs on microalgae, the post-exposure consequences remain largely unexplored. In this study, Microcystis aeruginosa was exposed to 5 and 50 mg/L of polystyrene (PS) for 15 days, followed by a 15-day post-exposure period in PS-free medium. Exposure to 5 mg/L PS did not significantly affect growth, phycobiliprotein content, or oxidative stress responses. In contrast, 50 mg/L PS significantly inhibited algal growth and impaired photosynthetic capacity. Transcriptomic analysis revealed that this toxicity was underpinned by a broad downregulation of central energy metabolism, including photosynthesis, glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation. Notably, following the removal of PS, M. aeruginosa exhibited a remarkable recovery capacity driven by metabolic rebound. This was manifested as a robust upregulation of previously suppressed pathways, particularly the pentose phosphate pathway and oxidative phosphorylation, facilitating a substantial, though potentially incomplete, restoration of physiological function. These findings highlight the metabolic resilience of M. aeruginosa and underscore the importance of considering post-exposure phases in ecological risk assessments of NPs.
Wang et al. (Mon,) studied this question.