Dispersion of TiO2 Nanoparticle Agglomerates by Pseudomonas aeruginosa
Dispersion of TiO2 Nanoparticle Agglomerates by Pseudomonas aeruginosa
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DOI：
10.1128/aem.00324-10
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发表时间：
2010-11-01
影响因子：
4.4
通讯作者：
Holden, Patricia A.
中科院分区：
文献类型：
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作者：
Horst, Allison M.;Neal, Andrea C.;Holden, Patricia A.
工程纳米颗粒越来越多地被纳入消费品中，并成为潜在的环境污染物。实验室研究证明，在环境释放后，纳米颗粒可以抑制细菌过程。关于纳米颗粒的细菌改变，包括细菌是否影响控制纳米颗粒沉降和生物利用度的物理团聚状态，知之甚少。在这里，铜绿假单胞菌的环境菌株对在水性介质中形成的TiO 2纳米颗粒团聚体的影响进行了描述。环境扫描电子显微镜和低温扫描电子显微镜直观地证明了在细胞培养基和沼泽水中形成的大团聚体的细菌分散体。对于细胞培养基中的实验，定量图像分析证实，大团聚体转化为小纳米颗粒-细胞组合的程度对于12小时生长和短期细胞接触实验是相似的。分散在细胞生长培养基中的进一步特征在于通过尺寸分级：对于团聚的TiO 2悬浮液在没有细胞的情况下，81%的质量保留在5 μ m孔径的过滤器上，相比之下，只有24%保留生物治疗。滤液细胞和团聚体的大小，其特征在于通过动态光散射，揭示了平均细菌细胞大小从1.4 μ m增加到1.9 μ m，因为纳米二氧化钛的生物吸附。高放大倍数的扫描电子显微镜照片显示，铜绿假单胞菌分散二氧化钛团聚体的优先生物吸附的纳米粒子到细胞表面上。这些结果表明细菌在工程纳米颗粒的环境运输中的新作用，即，生长独立的，细菌介导的大小和质量的TiO 2纳米颗粒团聚体的变化。
Engineered nanoparticles are increasingly incorporated into consumer products and are emerging as potential environmental contaminants. Upon environmental release, nanoparticles could inhibit bacterial processes, as evidenced by laboratory studies. Less is known regarding bacterial alteration of nanoparticles, including whether bacteria affect physical agglomeration states controlling nanoparticle settling and bioavailability. Here, the effects of an environmental strain of Pseudomonas aeruginosa on TiO2 nanoparticle agglomerates formed in aqueous media are described. Environmental scanning electron microscopy and cryogenic scanning electron microscopy visually demonstrated bacterial dispersion of large agglomerates formed in cell culture medium and in marsh water. For experiments in cell culture medium, quantitative image analysis verified that the degrees of conversion of large agglomerates into small nanoparticle-cell combinations were similar for 12-h-growth and short-term cell contact experiments. Dispersion in cell growth medium was further characterized by size fractionation: for agglomerated TiO2 suspensions in the absence of cells, 81% by mass was retained on a 5-mu m-pore-size filter, compared to only 24% retained for biotic treatments. Filtrate cell and agglomerate sizes were characterized by dynamic light scattering, revealing that the average bacterial cell size increased from 1.4 mu m to 1.9 mu m because of nano-TiO2 biosorption. High-magnification scanning electron micrographs showed that P. aeruginosa dispersed TiO2 agglomerates by preferential biosorption of nanoparticles onto cell surfaces. These results suggest a novel role for bacteria in the environmental transport of engineered nanoparticles, i.e., growth-independent, bacterially mediated size and mass alterations of TiO2 nanoparticle agglomerates.