With the accelerated application of CeO₂ nanoparticles (NPs), wastewater treatment plants will increasingly receive CeO₂ NPs, thus inevitably causing CeO₂ 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 CeO₂ NPs concentrations, with a particular emphasis on the protective mechanisms of stratified extracellular polymeric substances (EPSs). Chronic exposure to 0.1 mg/L CeO₂ 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 CeO₂ NPs. After the bacteria were exposed to CeO₂ 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 CeO₂ NPs. Furthermore, long-term exposure to CeO₂ 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 CeO₂ NPs. These results expand the understanding of how microaggregates resist environmental stress caused by NPs.

随着CeO ₂纳米颗粒（NPs）的加速应用，废水处理厂将越来越多地接受CeO ₂ NPs，因此不可避免地导致CeO ₂ NPs遇到微团聚体。在这里，我们全面阐明了废水生物膜在结构，物理化学和微生物特性方面对不同浓度的CeO ₂ NPs长期暴露（75天）的反应，特别强调了分层的细胞外聚合物（EPS）的保护机制。长期暴露于0.1 mg / L CeO _2中NP增加了α-D-吡喃葡萄糖多糖（PS）的含量并扩大了其分布范围，而β-D-吡喃葡萄糖PS的产量和广度急剧增加，形成了强大的屏蔽，是对10 mg / L CeO ₂ NP的响应。细菌暴露于CeO ₂ NP后，松散结合的EPS（LB-EPS）聚集成大分子（表观分子量（AMW）增加），但丰度较低，而紧密结合的EPS（TB-EPS）的平均AMW减少了。TB-EPS的乙酰基含量和（α-螺旋+3转螺旋）/β-片层值增加以抵抗CeO ₂ NPs。此外，长期暴露于CeO ₂NP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-高丝氨酸内酯的浓度随着假单胞菌密度的增加而增加，这与PS调控的控制有关，从而响应于CeO ₂ NPs促进EPS中PS的产生。这些结果扩大了对微聚集体如何抵抗由NP引起的环境压力的理解。