Copper Nanoparticle Interactions with Nitrogen-Cycling Bacteria

铜纳米粒子与氮循环细菌的相互作用

• 批准号: 1134355
• 负责人: Shaily Mahendra
• 金额: $ 30万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1134355&HistoricalAwards=false
• 关键词: Copper; Nanoparticle; Interactions; Nitrogen; Cycling

1134355MahendraThis NSF award by the Environmental Health and Safety of Nanotechnology program supports work by Professor Shaily Mahendra to examine the effects of copper nanoparticles (NPs) on the diversity and function of bacteria involved in nitrogen cycling in natural and engineered environmental systems.Background and Significance. We anticipate that in the next few decades, the inputs of engineered nanomaterial-containing products to waste streams will increase, and more plants will be required to carry out tertiary treatment of wastewater. Transformations of nitrogen in the environment are microbially driven; nitrification, denitrification, and nitrogen fixation are catalyzed by specific enzymes, which are sensitive to environmental disturbances and pollution. Additionally, nitrogen management is a significant challenge in agriculture and in wastewater treatment. The rapid growth in production and use of nanomaterials in commercial products has raised concerns about their potential adverse effects on the environment. Our current understanding of the mechanisms of uptake and toxicity towards microorganisms is limited. Furthermore, most toxicological studies evaluate ?manufactured materials? rather than the forms attained after undergoing environmental transformations. We will investigate the regulation of relevant enzymes in pure cultures as well as consortia, thus, addressing issues important to NSF missions of generating a predictive methodology of understanding and mitigating the potential harmful effects of the interaction of NPs with the environment. Intellectual Merits. This study will test the hypothesis that copper NPs will selectively affect the population, diversity, and activity of bacterial communities involved in nitrogen cycling based on specific nature of NP-cell interactions (ionic copper uptake versus NP uptake; external versus internal dissolution followed by reactive oxygen species (ROS) generation and membrane/DNA/ATP damage; etc.). While there are a few recent reports of short-term toxic effects of NPs on laboratory pure cultures, the novel aspects of this proposal include evaluating NPs? effects on a class of indigenous microorganisms, and the environmental roles they play, over longer time scales. In addition, this will be the first study to explore high-throughput screening (HTS) for evaluating dose-response characteristics as well as mechanisms of NP toxicity. Specific objectives include: (a) to determine the microbial impacts of copper NPs via standard physiological and HTS assays, (b) to investigate the effect of copper NPs on functional gene expression in several pure cultures of nitrifying, denitrifying, anammox, and nitrogen-fixing bacteria in order to identify most susceptible microbial process in the N cycle, and (c) to quantify and model changes in population and diversity of N-cycling bacterial communities, including the effect of intrafloc transport resistance on availability of ionic and particulate copper, nutrients and electron acceptors. pure cultures and microcosms, effect of NPs on the expression of relevant genes will be determined using enzyme-specific assays as well as RT-qPCR. Ultimately, the methodology employed herein will serve as a template to address NP hazard identification and risk assessment, safe design and implementation of nanotechnology, as well as management of global carbon and nitrogen cycles.Broader Impacts. The broader impacts of the proposed research extend beyond a better understanding of NP interactions with environmentally relevant bacteria. In addition to publications and presentations at scientific meetings, the findings will be translated into a series of lectures to be presented in a new graduate course on Environmental Biotechnology and a redesigned undergraduate course on Environmental Nanotechnology (both taught by the PI). Further, the PI will collaborate with a middle school in Los Angeles Unified School District to develop curriculum for a new environmental science class as well as hands-on activities in the Go Green horticultural club to describe the role of bacteria in environmental cycling of essential elements and assessing the impacts of toxic chemicals. Finally, the PI will serve as the faculty adviser for UCLA chapter of the Society of Women Engineers (SWE), and participate, with the funded Ph.D. students, in meetings and outreach activities.

1134355Mahendra 这项由纳米技术环境健康与安全项目颁发的 NSF 奖项支持 Shaily Mahendra 教授研究铜纳米颗粒 (NP) 对自然和工程环境系统中参与氮循环的细菌多样性和功能的影响。背景和意义。 我们预计，在未来几十年内，含有工程纳米材料的产品对废物流的投入将会增加，并且将需要更多的工厂对废水进行三级处理。 环境中氮的转化是由微生物驱动的；硝化、反硝化和固氮是由特定酶催化的，对环境干扰和污染敏感。 此外，氮管理是农业和废水​​处理中的重大挑战。 纳米材料在商业产品中的生产和使用的快速增长引起了人们对其对环境潜在不利影响的担忧。 我们目前对微生物的吸收和毒性机制的了解是有限的。 此外，大多数毒理学研究评估“制造材料”。而不是经历环境转变后所获得的形式。 我们将研究纯培养物和联合体中相关酶的调节，从而解决对 NSF 使命重要的问题，即生成理解和减轻纳米颗粒与环境相互作用的潜在有害影响的预测方法。智力优点。 本研究将检验铜纳米颗粒将根据纳米颗粒与细胞相互作用的具体性质（离子铜摄取与纳米颗粒摄取；外部溶解与内部溶解，然后反应）选择性地影响参与氮循环的细菌群落的种群、多样性和活性的假设。氧物质（ROS）的产生和膜/DNA/ATP损伤等）。 虽然最近有一些关于 NP 对实验室纯培养物的短期毒性作用的报道，但该提案的新颖之处包括评估 NP？在较长时间内对一类本土微生物的影响及其在环境中发挥的作用。 此外，这将是第一项探索高通量筛选（HTS）以评估剂量反应特征以及纳米粒子毒性机制的研究。 具体目标包括：（a）通过标准生理学和 HTS 测定确定铜纳米颗粒对微生物的影响，（b）研究铜纳米颗粒对硝化、反硝化、厌氧氨氧化和氮的几种纯培养物中功能基因表达的影响。固定细菌，以确定氮循环中最敏感的微生物过程，以及（c）对氮循环细菌群落的种群和多样性的变化进行量化和建模，包括絮体内运输阻力对可用性的影响离子和颗粒铜、营养物和电子受体。在纯培养物和微观世界中，纳米颗粒对相关基因表达的影响将使用酶特异性测定以及 RT-qPCR 来确定。 最终，本文采用的方法将作为解决纳米颗粒危害识别和风险评估、纳米技术的安全设计和实施以及全球碳和氮循环管理的模板。更广泛的影响。 拟议研究的更广泛影响超出了对纳米粒子与环境相关细菌相互作用的更好理解。 除了在科学会议上发表出版物和演讲外，研究结果还将转化为一系列讲座，在新的环境生物技术研究生课程和重新设计的环境纳米技术本科课程（均由 PI 教授）中进行介绍。 此外，PI 将与洛杉矶联合学区的一所中学合作，开发新的环境科学课程以及 Go Green 园艺俱乐部的实践活动，以描述细菌在基本元素的环境循环中的作用并评估有毒化学品的影响。 最后，PI 将担任加州大学洛杉矶分校女工程师协会 (SWE) 分会的教职顾问，并与受资助的博士一起参与。学生，参加会议和外展活动。