Metabolomic analysis reveals contrasting effects of PFOS and PFAS on cyanobacterial bloom and metabolic pathways in eutrophic water

Per- and polyfluoroalkyl substances (PFAS) are widespread in the aquatic environment, and the toxic effects of individual compounds on microalgae have been extensively documented. However, the differences in the impacts of single versus combined PFAS exposures on cyanobacterial blooms are still ambiguous. Herein, we explored the impacts and mechanisms of both single perfluorooctane sulfonate (PFOS) and combined PFAS exposure on Microcystis aeruginosa (M. aeruginosa) bloom under eutrophic conditions. The results indicated that PFOS suppresses algal bloom by diminishing growth rates and photosynthetic capabilities, accompanied by elevated expression of microcystin toxins and the induction of oxidative stress. Conversely, PFAS at environmentally relevant concentrations promote cyanobacteria bloom by enhancing growth rates and photosynthetic activity. Metabolomics analyses revealed that PFOS disrupts cell energy metabolism, reducing energy production and enhancing fatty acid synthesis. Additionally, PFOS disrupts purine metabolism, downregulating pyrimidine and amino acid metabolism. On the other hand, PFAS boosts the tricarboxylic acid cycle, upregulates amino acid synthesis, intensifies nucleotide metabolism, maintains the intracellular antioxidant system, and promotes algal growth. This study highlights the differences in the impacts of various perfluorinated compound exposure patterns on cyanobacterial bloom, offering new insights for improved water environment management.