Toxicity mechanism of cerium oxide nanoparticles on cyanobacteria Microcystis aeruginosa and their ecological risks

The extensive application of cerium oxide nanoparticles (CeO2 NPs), a type of rare earth nanomaterial, led to pollution into aquatic environments. Cyanobacteria, a significant component of freshwater ecosystems, can interact with CeO2 NPs. However, little attention has been paid as to whether CeO2 NPs will have adverse effects on cyanobacteria. In the present study, Microcystis aeruginosa (FACHB-942) was exposed to different concentrations (0, 1, 10, and 50 mg/L) of CeO2 NPs. Results showed 50 mg/L CeO2 NPs inhibited algal growth (11.48% +/- 5.76%), suppressed photosynthesis and induced the generation of reactive oxygen species (ROS) after 72 h exposure. The toxicity mechanism is the adsorption of CeO2 NPs on cell surface, the ROS formation and the intracellular Ce. Additionally, the intracellular microcystins (MCs) content was significantly induced (11.84% +/- 1.47%) by 50 mg/L CeO2 NPs, while no significance was found in 1 and 10 mg/L CeO2 NP treatments. Results indicated high concentrations of CeO2 NPs could be toxic to algae through the adverse effects on algal growth and photosynthesis. Moreover, the promoted MCs production could also pose a threat to freshwater ecosystems due to the possible release into the environment.

Automated summary

The present study found that high concentrations of cerium oxide nanoparticles (CeO2 NPs) had adverse effects on Microcystis aeruginosa, inhibiting algal growth, suppressing photosynthesis, and inducing the generation of reactive oxygen species (ROS). Additionally, the high concentration of CeO2 NPs significantly induced the production of intracellular microcystins (MCs), posing a potential threat to freshwater ecosystems.