Unraveling at Micro- and Macro-scale the Mineral Surface Reactions of Amino Acids and Small Peptides Using Phage Display Technology Coupled with Synchrotron-Based Spectroscopy

智力优势：最新的陆地N循环范式认为，可溶性有机氮(SON)是调节生态系统中总体N有效性的速率限制步骤。我们缺乏对土壤矿物和SON化合物之间相互作用的微观过程/机制的了解，这阻碍了我们在生态系统尺度上预测不同土壤区块之间的氮通量的能力。为了解决这一问题，提出了一种结合了一系列新的分子、生物和同步加速器光谱技术的跨学科方法来研究土壤矿物与氨基酸和小肽之间的相互作用机制。将使用新的方法来实现这一研究。噬菌体展示技术将用于在短时间内筛选出对特定矿物表面具有选择性亲和力的那些肽的数十亿个随机小肽序列。获得了氨基酸和小肽在土壤中常见的四种矿物上的宏观吸附等温线。利用从吸附等温线实验中收集的样品，利用偏振相关的N(1s)近边X射线吸收精细结构(NEXAFS)在微观尺度上研究了分子的平均表面取向。最后，将使用微生物论文方法在微观尺度上了解矿物表面的分子表面结构如何影响吸附的氨基酸和小肽的微生物利用。广泛影响：PI正在与当地两所高中(密西西比州数学与科学学校和西奥克提贝哈县高中)合作，招募未来的少数民族本科生参加暑期研究项目。这些暑期研究项目将为少数族裔高中生提供机会，获得在生物地球化学研究和最先进的仪器方面的经验，深入了解本科生和研究生的性质，与大学教授和研究生作为一个跨学科团队合作，并就如何促进他们未来的职业生涯做出明智的选择。学生还将有机会参加区域或国家会议并参观国家实验室。这些学生的工作和这项提案的研究将在他们的高中展示，并在州比赛中突出显示，如密西西比科学院的工程博览会和青年科学家分部。

Intellectual merit: The latest terrestrial N cycle paradigm considers soluble organic nitrogen (SON) as a rate limiting step for regulating the overall N availability in ecosystems. Our lack of understanding of the micro-scale processes/mechanisms of interactions between soil minerals and SON compounds hinders our ability to predict N flux between different soil compartments at the ecosystem-scale. To address this issue, an interdisciplinary approach that combines a broad array of novel molecular, biological, and synchrotron-based spectroscopic techniques is proposed to investigate the interaction mechanisms between soil minerals and amino acids and small peptides, two key components of soil SON. Novel methods will be used to achieve the research. The phage display technique will be used to screen, in a short period of time, billions of random small peptide sequences for those peptides displaying a selective affinity for a particular mineral surface. Macro-scale adsorption isotherms for amino acids and small peptides on four minerals commonly found in soil will be obtained. Using the samples collected from the adsorption isotherms experiment, polarization-dependent N (1s) near-edge x-ray absorption fine structure (NEXAFS) will be used to investigate, at micro-scale, the average molecular surface orientation. Lastly, a microbial essay method will be used to understand at micro-scale how molecular surface organization on mineral surfaces affects the microbial utilization of adsorbed amino acids and small peptides.Broader impacts: The PIs are cooperating with two local high schools (The Mississippi School for Mathematics and Science and The West Oktibbeha County High School) to recruit future minority undergraduate students for summer research projects. Those summer research projects will provide minority high school students opportunities to gain hands?]on experience in biogeochemistry research and state of the art instrumentations, to obtain insight into the nature of both undergraduate and graduate school, to work with university professors and graduate students as an interdisciplinary team, and to have informed choices about how to advance their future career. The students will also be given the opportunity to attend regional or national meetings and to visit national laboratories. The work from these students and the research of this proposal will be showcased at their high schools and highlighted in state competitions such as the Engineering Fair and the Young Scientist Division at the Mississippi Academy of Science.