SitS: Environmentally-benign sensors for the detection of nitrogen and foraging for nitrogen in soil

该项目将开发新的传感技术，以监测和研究支持作物植物的土壤微生物的氮觅食。除碳之外，氮是所有生物最需要的营养物质。氮是产生生命的基本要素（如DNA、蛋白质）所必需的，而地上生物体内的大部分氮都来自植物。为了给作物提供氮，2019年全球共向农田施用了1.07亿吨氮肥。然而，施用的氮肥中只有不到一半能到达作物，其余大部分被土壤微生物转化为其他形式的氮，包括对全球变化有重大贡献的一氧化二氮（N2O）等气体。加深对土壤微生物如何觅食氮的了解对可持续农业和减缓全球变化的努力至关重要。该提案将开发非破坏性成像技术，检测土壤中的氮，并根据土壤微生物信号释放氮肥。这些工具将用于评估支持作物植物的有益真菌的氮觅食。该项目将通过团队科学课程培训研究生和本科生进行跨学科研究，从而促进劳动力的发展。这项研究将通过质量和能量平衡、微生物学和分析化学课程的教学模块与学生的教学相结合，并提供高级化学工程设计挑战。这项工作的知识将通过一次国际会议的讲习班向更广泛的科学界传播。本研究将开发新的传感技术来监测土壤中的氮，并将其应用于研究一种模式，即焦点微生物（丛枝菌根真菌）的觅食。传感技术将基于非破坏性的拉曼光谱探针，探测氮和水凝胶，探测AM真菌分泌的化合物，导致氮释放。本研究建立了基础知识和工程设计原则，以支持这些技术的发展，并为未来能够感知氮水平并按需释放氮的闭环设备奠定了基础。本研究有三个目标：1)开发检测土壤中不同形式氮的拉曼探针；2)评估AM真菌对不同形式氮的觅食；3)使用迭代方法开发水凝胶，当检测到土壤生物时，水凝胶可以覆盖探针并释放氮。具体来说，将开发两种传感器（拉曼和水凝胶），它们可以单独使用，也可以一起使用，以检测与土壤化学物质相关的生物功能。这项研究产生的知识可以影响许多领域。例如，原位氮检测或氮觅食在精准农业中有应用。拉曼探针氮传感器可以实时识别土壤中不同的氮形态，传感水凝胶可以根据真菌或植物的信号分子按需释放氮，从而最大限度地减少农业系统中氮素的流失。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will develop new sensing technologies to monitor and study nitrogen foraging by soil microbes that support crop plants. Next to carbon, nitrogen is the nutrient most necessary to all living organisms. Nitrogen is needed to produce the building blocks of life (e.g., DNA, proteins), and most nitrogen in aboveground living organisms is sourced from plants. To provide nitrogen for crops, worldwide in 2019, 107 million tons of nitrogen fertilizer were applied to agricultural fields. Yet less than half of applied nitrogen reaches crop plants, and much of the rest is converted by soil microbes into other forms of nitrogen, including gasses like nitrous oxide (N2O) that make significant contributions to global change. Increased understanding of how soil microbes forage for nitrogen is critical to sustainable agriculture and global change mitigation efforts. This proposal will develop non-destructive imaging technologies that sense nitrogen in soil and release nitrogen fertilizers in response to soil microbial signals. These tools will be used to assess nitrogen foraging by beneficial fungi that support crop plants. This project will enhance workforce development by training graduate and undergraduate students in interdisciplinary research through a Team Science course. This research will be integrated with teaching through educational modules for students in mass and energy balances, microbiology, and analytical chemistry courses, as well as providing senior chemical engineering design challenges. Knowledge from this work will be disseminated to the broader scientific community through a workshop at an international meeting.This research will develop new sensing technologies to monitor nitrogen in soils and apply them to study foraging of a model, focal microbe (arbuscular mycorrhizal (AM) fungi). Sensing technologies will be based on non-destructive Raman spectroscopy probes that sense nitrogen and hydrogels that sense compounds secreted by the AM fungi, resulting in nitrogen release. This research establishes the foundational knowledge and engineering design principles to support development of these technologies and establishes a foundation for future closed loop devices that would be capable of sensing nitrogen levels and releasing nitrogen on demand. This research has three objectives to: 1) Develop Raman probes that detect different forms of nitrogen in soil, 2) Evaluate foraging by AM fungi for different forms of nitrogen, and 3) Use an iterative approach to develop hydrogels that coat probes and release nitrogen when soil organisms are detected. Specifically, two sensors will be developed (Raman and hydrogel) that can be used independently or together to detect a biological function related to soil chemicals. The knowledge generated from this research could impact many fields. For example, in situ detection of nitrogen or nitrogen foraging has applications for precision farming. Raman probe nitrogen sensors could identify different nitrogen forms in soil spatially, in real time, and sensing hydrogels could release nitrogen on demand to fungi or plants based on their signaling molecules, potentially minimizing applied nitrogen loss in agricultural systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.