Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
Water Res. 2018 Apr 15;133:208-217. doi: 10.1016/j.watres.2018.01.031. Epub 2018 Jan 18.
With the accelerated application of CeO nanoparticles (NPs), wastewater treatment plants will increasingly receive CeO NPs, thus inevitably causing CeO NPs to encounter microaggregates. Here, we comprehensively elucidate the responses in the structural, physicochemical and microbial properties of wastewater biofilms to chronic exposure (75 days) to different CeO NPs concentrations, with a particular emphasis on the protective mechanisms of stratified extracellular polymeric substances (EPSs). Chronic exposure to 0.1 mg/L CeO NPs boosted the content and broadened the distribution of α-d-glucopyranose polysaccharides (PS), while the sharply increased production and breadth of β-d-glucopyranose PS, forming a formidable shield, was a response to 10 mg/L CeO NPs. After the bacteria were exposed to CeO NPs, loosely bound EPSs (LB-EPSs) aggregated into macromolecules (increasing in apparent molecular weight (AMW)) but at a lower abundance, whereas the average AMW in tightly bound EPSs (TB-EPSs) decreased. The acetyl content and (α-helix+3-turn helix)/β-sheet value of TB-EPSs increased to resist CeO NPs. Furthermore, long-term exposure to CeO NPs decreased cell viability, reduced microbial diversity and shifted the microbial composition. N-acylated-l-homoserine lactone concentrations increased with increased density of Pseudomonas, which was associated with PS-regulated control, thus promoting PS production in EPSs in response to CeO NPs. These results expand the understanding of how microaggregates resist environmental stress caused by NPs.
随着 CeO 纳米颗粒（NPs）的加速应用，污水处理厂将越来越多地接收 CeO NPs，从而不可避免地导致 CeO NPs 遇到微团聚体。在这里，我们全面阐明了废水生物膜的结构、物理化学和微生物特性对慢性暴露（75 天）于不同 CeO NPs 浓度的响应，特别强调分层细胞外聚合物（EPS）的保护机制。慢性暴露于 0.1mg/L CeO NPs 会增加 α-d-吡喃葡萄糖多糖（PS）的含量并拓宽其分布，而 10mg/L CeO NPs 会急剧增加 β-d-吡喃葡萄糖 PS 的产量和广度，形成一道坚固的屏障。暴露于 CeO NPs 后，松散结合的 EPS（LB-EPS）聚集成大分子（增加表观分子量（AMW）），但其丰度较低，而紧密结合的 EPS（TB-EPS）的平均 AMW 降低。TB-EPS 中的乙酰基含量和（α-螺旋+3 转角螺旋）/β-折叠值增加，以抵抗 CeO NPs。此外，长期暴露于 CeO NPs 会降低细胞活力，降低微生物多样性并改变微生物组成。N-酰化-l-高丝氨酸内酯浓度随着假单胞菌密度的增加而增加，这与 PS 调节控制有关，从而促进 EPS 中 PS 的产生以应对 CeO NPs。这些结果扩展了对微团聚体如何抵抗 NPs 引起的环境压力的理解。
