Université de Toulouse, UPS, INP, EcoLab (Laboratoire d'écologie fonctionnelle et environnement), 118 route de Narbonne, F-31062 Toulouse, France; CNRS, EcoLab, F-31062 Toulouse, France.
Aquat Toxicol. 2013 Nov 15;144-145:310-21. doi: 10.1016/j.aquatox.2013.09.024. Epub 2013 Oct 23.
Ecotoxicological experiments have been performed in laboratory-scale microcosms to investigate the sensitivity of phototrophic biofilm communities to the alachlor herbicide, in relation to the stages of phototrophic biofilm maturation (age of the phototrophic biofilms) and physical structure (intact biofilm versus recolonization). The phototrophic biofilms were initially cultivated on artificial supports in a prototype rotating annular bioreactor (RAB) with Taylor-Couette type flow under constant operating conditions. Biofilms were collected after 1.6 and 4.4 weeks of culture providing biofilms with different maturation levels, and then exposed to nominal initial alachlor concentration of 10 μg L(-1) in either intact or recolonized biofilms for 15 days in microcosms (mean time-weighted average concentration - TWAC of 5.52 ± 0.74 μg L(-1)). At the end of the exposure period, alachlor effects were monitored by a combination of biomass descriptors (ash-free dry mass - AFDM, chlorophyll a), structural molecular fingerprinting (T-RFLP), carbon utilization spectra (Biolog) and diatom species composition. We found significant effects that in terms of AFDM, alachlor inhibited growth of the intact phototrophic biofilms. No effect of alachlor was observed on diatom composition or functional and structural properties of the bacterial community regardless of whether they were intact or recolonized. The intact three-dimensional structure of the biofilm did not appear to confer protection from the effects of alachlor. Bacterial community structure and biomass level of 4.4 weeks - intact phototrophic biofilms were significantly influenced by the biofilm maturation processes rather than alachlor exposure. The diatom communities which were largely composed of mobile and colonizer life-form populations were not affected by alachlor. This study showed that the effect of alachlor (at initial concentration of 10 μg L(-1) or mean TWAC of 5.52 ± 0.74 μg L(-1)) is mainly limited to biomass reduction without apparent changes in the ecological succession trajectories of bacterial and diatom communities and suggested that carbon utilization spectra of the biofilm are not damaged resulting. These results confirmed the importance of considering the influence of maturation processes or community age when investigating herbicide effects. This is particularly important with regard to the use of phototrophic biofilms as bio-indicators.
已经在实验室规模的微宇宙中进行了生态毒理学实验，以研究光养生物膜群落对甲草胺除草剂的敏感性，这与光养生物膜成熟阶段（光养生物膜的年龄）和物理结构（完整生物膜与再殖民化）有关。光养生物膜最初在带有泰勒-库埃特型流的原型旋转环生物反应器（RAB）中的人工载体上培养，在恒定的操作条件下。在培养 1.6 和 4.4 周后，收集生物膜，提供不同成熟水平的生物膜，然后将其暴露于 15 天的微宇宙中初始甲草胺浓度为 10 μg L(-1) 的完整或再殖民化生物膜中（时间加权平均浓度 - TWAC 为 5.52 ± 0.74 μg L(-1)）。在暴露期结束时，通过生物量描述符（无灰干质量 - AFDM、叶绿素 a）、结构分子指纹图谱（T-RFLP）、碳利用光谱（Biolog）和硅藻物种组成相结合来监测甲草胺的影响。我们发现，在 AFDM 方面，甲草胺对完整的光养生物膜的生长有显著的抑制作用。无论生物膜是完整的还是再殖民化的，甲草胺都没有观察到对硅藻组成或细菌群落的功能和结构特性的影响。生物膜的完整三维结构似乎并没有提供免受甲草胺影响的保护。生物膜成熟过程而不是甲草胺暴露对 4.4 周 - 完整光养生物膜的细菌群落结构和生物量水平有显著影响。主要由移动和定植生活型种群组成的硅藻群落不受甲草胺的影响。这项研究表明，甲草胺（初始浓度为 10 μg L(-1) 或平均 TWAC 为 5.52 ± 0.74 μg L(-1)）的影响主要限于生物量减少，而细菌和硅藻群落的生态演替轨迹没有明显变化，并表明生物膜的碳利用光谱没有受损。这些结果证实了在研究除草剂影响时考虑成熟过程或群落年龄影响的重要性。这对于将光养生物膜用作生物指标尤为重要。
