Predicting Chemical Transformations of Extracellular Biochemicals: The Role of Iron and Manganese (Hydr)Oxides

生物产生的生化物质在周围环境中发挥着多种功能。浓度通过生物降解、细胞外酶的作用以及与溶解的和微粒结合的地球化学物质的化学反应而降低。假设：(1)铁和锰（氢）氧化物普遍存在于土壤和沉积物中，是排泄生物化学物质的主要汇。(2)根据生物化学结构中活性官能团的身份、数量和排列，可以预测这些化学反应的途径和速率。目的：了解生化结构和化学反应性之间的关系，以此作为预测反应途径和速率的基础。为了说明我们的方法，以真菌产生的抗生素青霉素和霉菌产生的展霉素为例。为了使这些化学物质在土壤中保持足够长的时间以杀死致病细菌或竞争细菌，它们必须能够抵抗铁和锰（氢）氧化物的氧化。除了直接研究这两种生物化学物质外，我们还将研究亚结构Y1和Y2，以了解更多关于官能团的排列如何影响铁和锰（氢）氧化物的氧化途径和速率。群体感应（QS）信号化合物和QS抑制剂化合物是这项工作的重要方面。将着重讨论铁（OH）3（水合铁）和铁ooh（针铁矿）的氧化和水解反应。智力优势：提议的工作是地球化学，物理有机化学和微生物/生态学之间的桥梁。它促进了一项新的活动：预测新发现的生物化学物质的化学转化途径和速率，作为它们的结构/官能团和普遍的地球化学条件的函数。进一步了解特定细胞外生物化学物质的地球化学背景，反过来将鼓励分子生物学家寻找新的天然产物和调节机制。更广泛的影响：拟议工作的性质吸引学生跨越传统的学科界限，并使他们参与新的探究。在PI的实验室里，本科生改变了他们的专业轨迹，例如从化学工程到植物科学，从化学到环境工程，从地理到环境化学。PI的13名博士毕业生中有9名是女性。其中一人目前在分子生物学领域从事博士后工作。在这个项目中，我们从代表性不足的背景中寻找具有这些专业轨迹的新兵。这项工作的目标之一是编写不同层次的教程，一个面向高中生和普通大众，一个面向本科生，一个面向研究生和研究人员。通过这种方式，个人将获得以前无法获得的信息，并将受到启发，扩展和探索新的领域。

Biochemicals produced by organisms perform a diverse array of functions in the surrounding environment. Concentrations are decreased through biodegradation, the action of extracellular enzymes, and chemical reactions with dissolved and particulate-bound geochemicals.Hypotheses: (1) Iron and manganese (hydr)oxides, prevalent in soils and sediments, are major sinks for excreted biochemicals. (2) Pathways and rates of these chemical reactions can be predicted based on knowledge of the identity, number, and arrangement of reactive functional groups within the biochemical structure.Objective: develop an understanding of relationships between biochemical structure and chemical reactivity that can serve as the basis for predicting pathways and rates of reaction. To illustrate our approach, consider the antibiotics penicillic acid, produced by fungi, and patulin, produced by mold. For these chemicals to persist long enough in soils to kill pathogenic or competitor bacteria, they must be resistant to oxidation by iron and manganese (hydr)oxides. In addition to studying the two biochemicals directly, we will also examine substructures Y1 and Y2 to learn more about how the arrangement of functional groups affect pathways and rates of oxidation by iron and manganese (hydr)oxides. Quorum-sensing (QS) signal compounds and QS inhibitor compounds are important aspects of this work. Oxidation and hydrolysis reactions involving Fe(OH)3(ferrihydrite) and FeOOH(goethite) will be emphasized.Intellectual Merit: The proposed work serves as a bridge between geochemistry, physical organic chemistry, and microbiology/ecology. It facilitates a new activity: predicting pathways and rates of chemical transformation for newly-discovered biochemicals as a function of their structure/functional groups and prevalent geochemical conditions. Greater appreciation for the geochemical context for particular extracellular biochemicals, in turn, will encourage molecular biologists to seek novel natural products and regulatory mechanisms.Broader Impacts: The nature of the proposed work entices students to cross traditional disciplinary boundaries, and engages them in new lines of inquiry. Undergraduates have changed their professional trajectories while in the PI's laboratory, e.g. from Chemical Engineering to Plant Science, from Chemistry to Environmental Engineering, from Geography to Environmental Chemistry. Nine of the PI's thirteen PhD graduates are women. One is now performing postdoctoral work in Molecular Biology. For this project, we seek recruits from underrepresented backgrounds that have these professional trajectories in mind.One goal for the proposed work is to write tutorials at different levels, one for high school students and the general public, one for undergraduates, one for graduate students and researchers. In this way, individuals will have access to information that had not been available to them previously, and will be inspired to branch out and explore new fields.