Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus of Gualtar, 4710-057, Braga, Portugal.
Microb Ecol. 2011 Jul;62(1):58-68. doi: 10.1007/s00248-011-9861-4. Epub 2011 May 7.
The extensive use of nanometal-based products increases the chance of their release into aquatic environments, raising the question whether they can pose a risk to aquatic biota and the associated ecological processes. Aquatic microbes, namely fungi and bacteria, play a key role in forested streams by decomposing plant litter from terrestrial vegetation. Here, we investigated the effects of nanocopper oxide and nanosilver on leaf litter decomposition by aquatic microbes, and the results were compared with the impacts of their ionic precursors. Alder leaves were immersed in a stream of Northwest Portugal to allow microbial colonization before being exposed in microcosms to increased nominal concentrations of nanometals (CuO, 100, 200 and 500 ppm; Ag, 100 and 300 ppm) and ionic metals (Cu(2+) in CuCl(2), 10, 20 and 30 ppm; Ag(+) in AgNO(3), 5 and 20 ppm) for 21 days. Results showed that rates of leaf decomposition decreased with exposure to nano- and ionic metals. Nano- and ionic metals inhibited bacterial biomass (from 68.6% to 96.5% of control) more than fungal biomass (from 28.5% to 82.9% of control). The exposure to increased concentrations of nano- and ionic metals decreased fungal sporulation rates from 91.0% to 99.4%. These effects were accompanied by shifts in the structure of fungal and bacterial communities based on DNA fingerprints and fungal spore morphology. The impacts of metal nanoparticles on leaf decomposition by aquatic microbes were less pronounced compared to their ionic forms, despite metal ions were applied at one order of magnitude lower concentrations. Overall, results indicate that the increased release of nanometals to the environment may affect aquatic microbial communities with impacts on organic matter decomposition in streams.
纳米金属基产品的广泛使用增加了它们释放到水生环境中的机会，这引发了一个问题，即它们是否会对水生生物区系和相关的生态过程构成风险。水生微生物，即真菌和细菌，通过分解来自陆地植被的植物凋落物，在森林溪流中发挥着关键作用。在这里，我们研究了纳米氧化铜和纳米银对水生微生物分解叶凋落物的影响，并将结果与它们的离子前体的影响进行了比较。在葡萄牙西北部的溪流中浸泡桦木叶，使微生物在微宇宙中接触到增加的纳米金属（CuO，100、200 和 500 ppm；Ag，100 和 300 ppm）和离子金属（CuCl2 中的 Cu(2+)，10、20 和 30 ppm；AgNO3 中的 Ag(+)，5 和 20 ppm）21 天。结果表明，叶片分解率随纳米金属和离子金属的暴露而降低。纳米金属和离子金属抑制细菌生物量（从对照的 68.6%到 96.5%）多于真菌生物量（从对照的 28.5%到 82.9%）。暴露于较高浓度的纳米金属和离子金属会降低真菌孢子的繁殖率，从 91.0%到 99.4%。这些影响伴随着基于 DNA 指纹图谱和真菌孢子形态的真菌和细菌群落结构的变化。与离子形式相比，金属纳米颗粒对水生微生物分解叶凋落物的影响较小，尽管金属离子的应用浓度低一个数量级。总体而言，研究结果表明，环境中纳米金属释放的增加可能会影响水生微生物群落，从而影响溪流中的有机物质分解。
