Université Clermont-Auvergne, CNRS, Laboratoire Microorganismes: Génome et Environnement, F-63000 Clermont-Ferrand, France.
Université Clermont-Auvergne, CNRS, Laboratoire Microorganismes: Génome et Environnement, F-63000 Clermont-Ferrand, France.
Sci Total Environ. 2017 Apr 15;584-585:1084-1092. doi: 10.1016/j.scitotenv.2017.01.167. Epub 2017 Jan 31.
The present study investigates the sensitivity of laccase activity to the fungicide tebuconazole (TBZ) in order to seek for new functional toxicity descriptors in aquatic microbial communities associated to decomposing litter. With this aim, we analyzed the sensitivity of laccase from the different microbial components (fungi and bacteria growing separately and in co-existence), as well as that of their corresponding enzyme fractions (cell bound and diffusible), forming microbial communities in Alnus glutinosa leaves. Results show that fungi are pivotal for laccase activity in leaves and that their activity is repressed when they co-exist with bacteria. The sensitivity of laccase activity to the TBZ was only detectable in leaves colonized by fungi separately (Alatospora acuminata populations), but absent in those colonized by bacteria separately and/or mixed fungi plus bacteria. Specifically, the increase of TBZ concentration enhances laccase activity in Alatospora acuminata populations but decreases ergosterol concentration as well as the amount of 18S RNA gene copies. This activity response suggests a detoxification mechanism employed by the fungus in order to reduce TBZ toxicity. Besides, enzyme fractioning showed that laccase activity in the cell bound fraction (76% of the total activity) was sensitive to the fungicide, but not that in the diffusible fraction (24% of total activity). Hence, TBZ would influence laccase activity in the presence of fungal cells but not in enzymes already synthesized in the extracellular space. The present study highlights the importance of the biological complexity level (i. e. population, community, ecosystem) when seeking for appropriate functional ecotoxicity descriptors in aquatic microbial communities.
本研究旨在探讨漆酶活性对杀菌剂戊唑醇（TBZ）的敏感性，以期在与分解落叶相关的水生微生物群落中寻找新的功能毒性描述符。为此，我们分析了来自不同微生物成分（真菌和细菌分别生长和共存时）的漆酶的敏感性，以及它们相应的酶级分（细胞结合和可扩散）在阿尔努斯 glutinosa 叶片中的微生物群落中的敏感性。结果表明，真菌是叶片中漆酶活性的关键，当它们与细菌共存时，其活性受到抑制。漆酶活性对 TBZ 的敏感性仅在真菌单独（尖锐曲霉种群）定植的叶片中可检测到，但在细菌单独定植和/或混合真菌加细菌定植的叶片中则不存在。具体而言，TBZ 浓度的增加会增强尖锐曲霉种群中的漆酶活性，但会降低麦角固醇浓度以及 18S RNA 基因拷贝数。这种活性响应表明真菌采用了一种解毒机制来降低 TBZ 的毒性。此外，酶分级表明细胞结合级分（总活性的 76%）中的漆酶活性对杀菌剂敏感，但可扩散级分（总活性的 24%）中的漆酶活性则不敏感。因此，在存在真菌细胞的情况下，TBZ 会影响漆酶活性，但不会影响已经在细胞外空间合成的酶的活性。本研究强调了在水生微生物群落中寻找适当的功能生态毒性描述符时，生物复杂性水平（即种群、群落、生态系统）的重要性。
