Mechanisms of PFBA toxicity in Chlorella vulgaris: Photosynthesis, oxidative stress, and antioxidant impairment

value of PFBA was 154.88 mg/L, which is comparable to conventional per- and polyfluoroalkyl substances (PFAS). Acute toxicity experiments revealed a biphasic dose-response relationship to the algal growth with the hormetic effects at the lower concentrations (30.97-92.93 mg/L) but inhibition at the higher levels (123.91-185.86 mg/L) of PFBA. High dosages of PFBA significantly decreased the maximum photosynthetic yield (Fv/Fm) and relative electron transfer rate (rETR), while inducing oxidative stress and inhibiting superoxide dismutase (SOD) and catalase (CAT) activities. Future AlphaFold2 modeling and molecular docking simulations demonstrated the potential binding of PFBA to photosystem II D1 C-terminal processing protease (PSII D1 protein), SOD, and CAT. These findings reveal a complex toxicity mechanism of PFBA on C. vulgaris involving photosynthetic disruption, oxidative stress, and antioxidant system impairment, contributing to the understanding of short-chain PFAS alternative ecotoxicity in aquatic ecosystems.