Investigating the Impact of Cerium Oxide Nanoparticles Upon the Ecologically Significant Marine Cyanobacterium Prochlorococcus
Investigating the Impact of Cerium Oxide Nanoparticles Upon the Ecologically Significant Marine Cyanobacterium Prochlorococcus
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DOI：
10.3389/fmars.2021.668097
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发表时间：
2021-05-19
影响因子：
3.7
通讯作者：
Davies, Gemma-Louise
中科院分区：
文献类型：
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作者：
Dedman, Craig J.;Rizk, Marwa M., I;Davies, Gemma-Louise
氧化铈纳米颗粒（nCeO 2）的使用率越来越高，然而，它们对水环境的影响仍然不确定。在这里，我们暴露的生态显着的海洋蓝藻原绿球藻属。MED 4 nCeO 2在很宽的浓度范围内（1 μ g L-1至100毫克L-1），在模拟的自然和营养丰富的生长条件下。蓝藻种群的流式细胞仪分析显示nCeO 2（100 μ g L-1）的潜力显着降低原绿球藻细胞密度在短期内（72小时）高达68.8%，在环境相关的条件下。然而，以下较长的曝光（240小时）蓝藻种群被观察到恢复模拟自然条件下。相比之下，在最佳条件下生长的细胞密集培养物在延长孵育期间对暴露更敏感，这可能是由于在高细胞密度下蓝藻和纳米颗粒之间的相遇率增加。暴露于超环境nCeO 2浓度（即，100 mg L-1）导致细胞密度显着下降高达95.7和82.7%，分别在天然贫营养海水和营养强化培养基。观察到的细胞下降与广泛的聚集行为nCeO 2进入天然海水后，观察到的动态光散射（DLS），和异源聚集与蓝藻，荧光显微镜证实。因此，认为细胞增殖的减少是由于与nCeO 2的共聚集和共沉降导致的物理去除，而不是毒理学和细胞死亡效应。在模拟的自然条件下观察到的蓝细菌种群的恢复，以及纳米颗粒聚集并在盐介质中沉淀时nCeO 2生物利用度的可能降低，意味着nCeO 2在海洋环境中可能的环境风险似乎很低。
Cerium oxide nanoparticles (nCeO2) are used at an ever-increasing rate, however, their impact within the aquatic environment remains uncertain. Here, we expose the ecologically significant marine cyanobacterium Prochlorococcus sp. MED4 to nCeO2 at a wide range of concentrations (1 mu g L-1 to 100 mg L-1) under simulated natural and nutrient rich growth conditions. Flow cytometric analysis of cyanobacterial populations displays the potential of nCeO2 (100 mu g L-1) to significantly reduce Prochlorococcus cell density in the short-term (72 h) by up to 68.8% under environmentally relevant conditions. However, following longer exposure (240 h) cyanobacterial populations are observed to recover under simulated natural conditions. In contrast, cell-dense cultures grown under optimal conditions appear more sensitive to exposure during extended incubation, likely as a result of increased rate of encounter between cyanobacteria and nanoparticles at high cell densities. Exposure to supra-environmental nCeO2 concentrations (i.e., 100 mg L-1) resulted in significant declines in cell density up to 95.7 and 82.7% in natural oligotrophic seawater and nutrient enriched media, respectively. Observed cell decline is associated with extensive aggregation behaviour of nCeO2 upon entry into natural seawater, as observed by dynamic light scattering (DLS), and hetero-aggregation with cyanobacteria, confirmed by fluorescent microscopy. Hence, the reduction of planktonic cells is believed to result from physical removal due to co-aggregation and co-sedimentation with nCeO2 rather than by a toxicological and cell death effect. The observed recovery of the cyanobacterial population under simulated natural conditions, and likely reduction in nCeO2 bioavailability as nanoparticles aggregate and undergo sedimentation in saline media, means that the likely environmental risk of nCeO2 in the marine environment appears low.Superscript/Subscript Available