Environment and Climate Change Canada, 11 Innovation Blvd., Saskatoon, SK, S7N 3H5, Canada.
Global Institute for Water Security, University of Saskatchewan, Saskatoon, SK, S7N 5A8, Canada.
Environ Pollut. 2020 Jan;256:113515. doi: 10.1016/j.envpol.2019.113515. Epub 2019 Oct 31.
Cerium oxide (CeO) nanoparticles are used as in-fuel catalysts and in manufacturing processes, creating a potential for release to aquatic environments. Exposures at 1 and 10 μg/L CeO-nanoparticles were made to assess effects during the development of river biofilm communities. Scanning transmission x-ray microscopy (STXM) indicated extensive sorption of nanoparticles to the community and co-localization with lipid moieties. Following 8 weeks of development, polycarbonate coupons were removed from the reactors and used for molecular analyses, denaturing gradient gel electrophoresis analysis (DGGE-16S rRNA) and 16S rRNA amplicon sequencing. Microscopic imaging of the biofilm communities (bacterial, photosynthetic biomass, exopolymer composition, thickness, protozoan numbers), as well as carbon substrate utilization fingerprinting was performed. There was a trend toward reduced photosynthetic biomass, but no significant effects of CeO exposure were found on photosynthetic and bacterial biomass or biofilm thickness. Sole carbon source utilization analyses indicated increased utilization of 10 carbon sources in the carbohydrate, carboxylic acid and amino acids categories related to CeO exposures; however, predominantly, no significant effects (p < 0.05) were detected. Measures of microbial diversity, lectin binding affinities of exopolymeric substances and results of DGGE analyses, indicated significant changes to community composition (p < 0.05) with CeO exposure. Increased binding of the lectin Canavalia ensiformis was observed, consistent with changes in bacterial-associated polymers. Whereas, no significant changes were observed in binding to residues associated with algal and cyanobacterial exopolymers. 16S rRNA amplicon sequencing of community DNA indicated changes in diversity and shifts in community composition; however, these did not trend with increasing CeO exposure. Counting of protozoans in the biofilm communities indicated no significant effects on this trophic level. Thus, based on biomass and functional measures, CeO nanoparticles did not appear to have significant effects; however, there was evidence of selection pressure resulting in significant changes in microbial community composition.
氧化铈（CeO）纳米颗粒被用作燃料内催化剂和制造工艺中的催化剂，从而有可能释放到水生环境中。在评估河流水体生物膜群落发育过程中的影响时，将浓度为 1 和 10μg/L 的 CeO 纳米颗粒进行了暴露实验。扫描透射 X 射线显微镜（STXM）表明，纳米颗粒广泛地被生物膜群落吸附，并且与脂质部分共定位。经过 8 周的发育，将聚碳酸酯（polycarbonate）小室从反应器中取出，用于分子分析、变性梯度凝胶电泳分析（DGGE-16S rRNA）和 16S rRNA 扩增子测序。对生物膜群落（细菌、光合作用生物量、胞外聚合物组成、厚度、原生动物数量）进行了微观成像，以及对碳底物利用指纹图谱进行了分析。生物量显示出光合作用生物量减少的趋势，但 CeO 暴露对光合作用生物量和细菌生物量或生物膜厚度没有显著影响。单一碳源利用分析表明，与 CeO 暴露相关的碳水化合物、羧酸和氨基酸类别中的 10 种碳源的利用增加；然而，主要是没有检测到显著影响（p<0.05）。微生物多样性的测量、胞外聚合物的凝集素结合亲和力以及 DGGE 分析的结果表明，群落组成发生了显著变化（p<0.05）。观察到伴刀豆球蛋白 Canavalia ensiformis 的结合增加，与与细菌相关的聚合物的变化一致。然而，与藻类和蓝藻胞外聚合物相关的残留物的结合没有观察到显著变化。对群落 DNA 的 16S rRNA 扩增子测序表明，多样性和群落组成发生了变化；然而，这些变化没有随 CeO 暴露的增加而呈现趋势。对生物膜群落中原生动物的计数表明，在这个营养水平上没有显著影响。因此，根据生物量和功能测量，CeO 纳米颗粒似乎没有产生显著影响；然而，有证据表明选择压力导致微生物群落组成发生了显著变化。
