The interaction between metal oxide nanoparticles and toxin-producing cyanobacteria is relatively unknown. The present work exposed Microcystis sp.7806 to different concentrations of cerium oxide nanoparticles (CeO₂ NPs) (1 mg/L, 10 mg/L and 50 mg/L), and evaluated the growth, photosynthetic activity, reactive oxygen species level, and the extra-(intra-) cellular microcystin-LR (MC-LR) contents. The particle size, zeta potential and cerium ions released into the medium were analyzed. Results showed 10 mg/L NP treatment promoted algae growth but slightly inhibited the photosynthetic yield of algae, and the 50 mg/L treatment reduced algae biomass. The algal cells remarkably responded to oxidative stress at higher concentrations (10 mg/L and 50 mg/L). CeO₂ NPs largely increased the intracellular MC-LR content at 50 mg/L, and significantly reduced the extracellular MC-LR content at any concentration. This demonstrates CeO₂ NPs may pose an ecological risk potential during harmful algal blooms by stimulating toxin production.

中文翻译：

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CeO2纳米颗粒对铜绿微囊藻生长和微囊藻毒素生产的影响。

金属氧化物纳米粒子和产生毒素的蓝细菌之间的相互作用是相对未知的。本研究将Microcystis sp .7806暴露于不同浓度的氧化铈纳米颗粒（CeO ₂ NPs）（1 mg / L，10 mg / L和50 mg / L），并评估了其生长，光合作用活性，活性氧水平，以及细胞内微囊藻毒素（MC-LR）的含量。分析了释放到培养基中的粒径，ζ电势和铈离子。结果表明，10 mg / L NP处理可促进藻类生长，但略微抑制藻类的光合产量，而50 mg / L NP处理可减少藻类生物量。在较高浓度（10 mg / L和50 mg / L）下，藻类细胞对氧化应激反应显着。首席执行官_2个NP在50 mg / L时大大增加了细胞内MC-LR的含量，并在任何浓度下均显着降低了细胞外MC-LR的含量。这表明CeO ₂ NPs可能通过刺激毒素产生而在有害藻华期间构成潜在的生态风险。