An investigation into the effects of nanoparticles on the bacterial diversity of freshwater and coastal marine sediments

纳米颗粒（NPs）是一种非常小的颗粒，尺寸在1-100纳米之间。具有抗菌特性的纳米产品正在迅速增加，这些产品被用于医药（无菌敷料、植入物）和家用产品（洗衣机、易清洁表面、衣服）。纳米银和二氧化钛（TiO2） NPs在这些产品中尤其普遍，生物医学研究表明这些材料具有抗菌作用（具有几种杀死细菌的模式，包括氧化应激）。人们担心这些材料会被释放到环境中，尤其是从家庭使用中释放出来，而这些抗菌特性会持续存在。我们已经证明TiO2 NPs对鱼类是有毒的，在这个为期一年的项目中，我们关注的是海洋和淡水沉积物中的微生物群落。细菌群落在水生食物网中发挥着重要作用，对沉积物的完整性和正常的养分循环、稳定性和功能地球化学至关重要。在这个提议中，我们测试了一个假设，即具有已知抗菌特性的工程NPs可以改变水生沉积物和上覆水中的细菌群落。我们的方法是使用从沿海海洋和淡水站点收集的自然沉积物和水，并在实验室中将它们暴露于纳米银或TiO2 NP中。细菌多样性将使用最先进的分子技术进行评估，包括从沉积物和上覆水中提取DNA。颗粒特性将涉及几种推荐的测量方法，并将监测水的pH值或盐度等化学因素。该项目汇集了细菌、沉积物/金属化学和纳米颗粒生态毒理学方面的专业知识。交付成果将包括在单独的实验中，在控制沉积物和水暴露于银和TiO2 NPs期间测量微生物多样性的时间过程。这将提供第一个重要的“原理证明”，即具有抗菌特性的NPs是否也可能对环境中的微生物有害。

Nanoparticles (NPs) are very small particles in the size range of 1-100 nanometers. There is a rapidly expanding list of nano-products which have anti-bacterial properties, and these are used in medicine (sterile dressings, implants) and in domestic products (washing machines, easy-clean surfaces, clothing). Nano silver and titanium dioxide (TiO2) NPs are especially prevalent in these products, and biomedical studies have shown these materials to be antibacterial (with several modes of bacterial killing including oxidative stress). There are concerns that these materials will be released into the environment, especially from domestic use, and that these anti-bacterial properties will persist. We have already shown that TiO2 NPs are toxic to fish, and in this one-year project we are concerned about the microbial communities in marine and freshwater sediments. Bacterial communities play important roles in aquatic food webs, and are vital to the integrity and normal nutrient cycling, stability, and functional geochemistry of sediments. In this proposal we test the hypothesis that engineered NPs with known anti-bacterial properties could alter bacterial communities in aquatic sediments and the overlying water. Our approach is to use field-collected natural sediments and water from coastal marine and freshwater sites, and expose these to either nano silver or TiO2 NP in the laboratory. Bacterial diversity will be assessed using state-of-the-art molecular techniques involving DNA extractions from the sediments and overlying water. Particle characterisation will involve several recommended measurements, and chemical factors such as water pH or salinity will be monitored. The project brings together expertise on bacteria, sediment/metal chemistry, and the ecotoxicology of nanoparticles. The deliverables will include measured time courses of microbial diversity during controlled sediment and water exposures to silver and TiO2 NPs in separate experiments. This will provide the first vital 'proof of principle' as to whether or not NPs with anti-bacterial properties could also be harmful to microorganisms in the environment.