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来监测和研究支持农作物的土壤微生物的氮觅食。除了碳之外，氮是所有生物体最必需的营养物质。氮是生产生命的组成部分（例如 DNA、蛋白质）所必需的，而地上生物体中的大多数氮都来自植物。为了给农作物提供氮肥，2019年全球农田施用了1.07亿吨氮肥。然而，只有不到一半的施氮到达农作物，其余大部分被土壤微生物转化为其他形式的氮，包括一氧化二氮 (N2O) 等对全球变化做出重大贡献的气体。加深对土壤微生物如何获取氮的了解对于可持续农业和减缓全球变化的努力至关重要。该提案将开发无损成像技术，感知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农作物的有益真菌的氮觅食。该项目将通过团队科学课程对研究生和本科生进行跨学科研究培训，从而加强劳动力发展。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育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国际会议上的研讨会向更广泛的科学界传播。这项研究将开发新的传感技术来监测土壤中的氮，并将其应用于研究模型、焦点微生物（丛枝菌根 (AM) 真菌）的觅食。传感技术将基于可感知氮的非破坏性拉曼光谱探针和可感知 AM 真菌分泌的化合物的水凝胶，从而释放氮。这项研究建立了支持这些技术开发的基础知识和工程设计原则，并为未来能够感应氮气水平并按需释放氮气的闭环设备奠定了基础。这项研究有三个目标：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，以及 3) 使用迭代方法开发水凝胶，该水凝胶可覆盖探针并在检测到土壤生物时释放氮。具体来说，将开发两种传感器（拉曼和水凝胶），它们可以单独或一起使用来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能会影响许多领域。例如，氮或氮觅食的原位检测可用于精准农业。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，从而有可能最大限度地减少农业系统中应用的氮损失。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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.