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生长的土壤微生物对氮素的觅食。氮是仅次于碳的所有生物最必需的营养物质。氮是生产生命的基石(如DNA、蛋白质)所必需的，而地上生物体中的大部分氮来自植物。为了给作物提供氮素，2019年全球农田氮肥施用量为1.07亿吨。然而，只有不到一半的氮肥进入农作物，其余的大部分被土壤微生物转化为其他形式的氮，包括对全球变化做出重大贡献的一氧化二氮(N2O)等气体。增加对土壤微生物如何觅食氮素的了解对于可持续农业和全球减缓变化的努力至关重要。这项提议将开发非破坏性成像技术，检测土壤中的氮素，并根据土壤微生物信号释放氮肥。这些工具将被用来评估支持农作物的有益真菌对氮素的觅食。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，从而促进劳动力发展。这项研究将通过为学生提供质量和能量平衡、微生物学和分析化学课程的教育模块来整合教学，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研讨会传播给更广泛的科学界。这项研究将开发新的传感技术来监测土壤中的氮，并将其应用于研究一种模型--局部微生物(丛枝菌根真菌)的觅食。传感技术将基于非破坏性拉曼光谱探头和水凝胶，拉曼光谱探头探测氮气，水凝胶探测AM真菌分泌的化合物，导致氮气释放。这项研究建立了支持这些技术发展的基础知识和工程设计原则，并为未来能够感知氮素水平并按需释放氮气的闭环系统奠定了基础。这项研究有三个目标：1)开发检测土壤中不同形态氮素的拉曼探针；2)评估AM真菌对不同形态氮素的觅食；3)使用迭代方法开发覆盖在探针上的水凝胶，并在检测到土壤生物时释放氮素。具体地说，将开发两种传感器(拉曼和水凝胶)，可以单独使用，也可以一起使用，以检测与土壤化学物质有关的生物功能。这项研究产生的知识可能会影响许多领域。例如，氮素的原位检测或氮素觅食在精准农业中有应用。拉曼探测器氮传感器可以在空间上实时识别土壤中不同的氮素形态，传感水凝胶可以根据真菌或植物的信号分子按需释放氮素，潜在地将农业系统中应用的氮素损失降至最低。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.