Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada.
Global Institute for Water Security, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Environ Toxicol Chem. 2019 Nov;38(11):2414-2425. doi: 10.1002/etc.4550. Epub 2019 Sep 26.
Studies of the South Saskatchewan River confirmed that N,N-diethyl-m-toluamide (DEET) is ubiquitous at 10 to 20 ng/L, whereas in effluent-dominated Wascana Creek, levels of 100 to 450 ng/L were observed. Effects of DEET exposure were assessed in microbial communities using a wide variety of measures. Communities developed in rotating annular reactors with either 100 or 500 ng/L DEET, verified using gas chromatography-mass spectrometry analyses. Microscale analyses indicated that both DEET concentrations resulted in significant (p < 0.05) declines in photosynthetic biomass, whereas bacterial biomass was unaffected. There was no detectable effect of DEET on the levels of chlorophyll a. However, pigment analyses indicated substantial shifts in algal-cyanobacterial community structure, with reductions of green algae and some cyanobacterial groups at 500 ng/L DEET. Protozoan/micrometazoan grazers increased in communities exposed to 500 ng/L, but not 100 ng/L, DEET. Based on thymidine incorporation or utilization of carbon sources, DEET had no significant effects on metabolic activities. Fluorescent lectin-binding analyses showed significant (p < 0.05) changes in glycoconjugate composition at both DEET concentrations, consistent with altered community structure. Principal component cluster analyses of denaturing gradient gel electrophoresis indicated that DEET exposure at either concentration significantly changed the bacterial community (p < 0.05). Analyses based on 16S ribosomal RNA of community composition confirmed changes with DEET exposure, increasing detectable beta-proteobacteria, whereas actinobacteria and acidimicrobia became undetectable. Further, cyanobacteria in the subclass Oscillatoriophycideae were similarly not detected. Thus, DEET can alter microbial community structure and function, supporting the need for further evaluation of its effects in aquatic habitats. Environ Toxicol Chem 2019;38:2414-2425. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
萨斯喀彻温河南部的研究证实，N,N-二乙基间甲苯酰胺（DEET）普遍存在于 10 至 20ng/L，而在以污水为主的瓦斯卡纳克里克，浓度为 100 至 450ng/L。使用各种方法评估了 DEET 暴露对微生物群落的影响。在带有 100 或 500ng/L DEET 的旋转环式反应器中培养微生物群落，并使用气相色谱-质谱分析进行验证。微尺度分析表明，两种 DEET 浓度都导致了光合生物量的显著（p<0.05）下降，而细菌生物量不受影响。DEET 对叶绿素 a 的水平没有可检测到的影响。然而，色素分析表明藻类-蓝细菌群落结构发生了重大变化，在 500ng/L 的 DEET 下，绿藻和一些蓝细菌群体减少。在暴露于 500ng/L 的 DEET 的群落中，原生动物/微型后生动物捕食者增加，但在 100ng/L 的 DEET 中没有增加。基于胸苷掺入或碳源利用，DEET 对代谢活性没有显著影响。荧光凝集素结合分析表明，在两种 DEET 浓度下，糖缀合物组成都发生了显著（p<0.05）变化，与群落结构的改变一致。变性梯度凝胶电泳的主成分聚类分析表明，两种浓度的 DEET 暴露都会显著改变细菌群落（p<0.05）。基于群落组成的 16S 核糖体 RNA 分析证实，DEET 暴露会引起变化，增加可检测的β变形菌，而放线菌和酸杆菌变得不可检测。此外，Oscillatoriophycideae 亚类的蓝细菌也同样未被检测到。因此，DEET 可以改变微生物群落结构和功能，支持对其在水生栖息地中的影响进行进一步评估的需要。Environ Toxicol Chem 2019;38:2414-2425。©2019 由 Wiley Periodicals, Inc. 代表 SETAC 出版的《环境毒理学与化学》。
