Defining Critical Roles of Siderophore Structures in Environmental Trace Metal Cycling

定义铁载体结构在环境微量金属循环中的关键作用

• 批准号: 0921313
• 负责人: Owen Duckworth
• 金额: $ 29.73万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0921313&HistoricalAwards=false
• 关键词: Defining; Critical; Roles; Siderophore; Structures

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The perceived environmental roles of siderophores, biogenic chelating agents exuded by organisms to increase the bioavailability of iron by complexation, have traditionally excluded the involvement of other important trace metals and focused largely on biologically facilitated iron solubilization and transport. Recent work has suggested that siderophores likely are involved in the biological solubilization and uptake of other environmentally important trace metals, including Cr, Mn, and Co. That siderophores may play important, possibly specific, roles with these other metals is suggested by the fact that siderophore complexes of these metals may have stability constants that equal or exceed those for ferric iron. The palette of siderophore-metal binding strengths that occurs across the periodic table, combined with the tendency for some cations to shuttle between oxidation states, suggests a rich but largely unexplored environmental chemistry. In spite of the imputed importance of these complexes in trace metal cycling and hence the primary productivity of soils and natural waters, significant gaps exist in our knowledge of their formation mechanisms, the structural factors that govern stability in solution and at mineral-water interfaces, and their environmental reactivity. A deeper understanding of these interactions is required to accurately describe the complicated role of siderophores in metal biogeochemistry. Seminal questions include: How effective are siderophores and siderophore-containing multi-ligand mixtures at solubilizing trace metals from minerals?; How stable are trace metal-siderophore complexes at surfaces and under environmentally relevant aqueous conditions?; How does the reactivity of metal-siderophore complexes couple to the biogeochemical cycling of other environmentally relevant species?; And, how do the structures of metal-siderophore complexes control their metal selectivity? This research project will utilize a complex formation-to-degradation approach to elucidate metal-siderophore complex behavior: formation of complexes by siderophore-promoted dissolution of metal (hydr)oxides; characterization of the stability and structure of aqueous and adsorbed metal-siderophore complexes; and quantitation of the reactivity of complexes with metal oxide surfaces, and the molecular-scale structures that give rise to this chemistry. It is now becoming apparent that siderophores engage in a diverse environmental chemistry, and that more complex paradigms are required to describe their effects on the biogeochemical cycling of trace metals beyond iron. The intellectual merit of the proposed work stems from the development of a new conceptual model to describe the multifaceted roles played by siderophores in the environment. A quantitative molecular-scale understanding of these processes will elucidate fundamental mechanisms by which siderophores affect the cycling of trace metals and forge linkages between these metals and other elements through biogeochemistry and geobiology. The broader impacts of the proposed work reach beyond basic discovery in the earth sciences to education, broad interdisciplinary scientific realms, and environmental management. The project will provide experience to an early-career scientist as well as a broad, multidisciplinary education to an NCSU graduate student and a team of Brooklyn College undergraduates. Duckworth helps to spearhead a series of visiting seminars at area colleges to recruit graduate students, especially from underrepresented groups. Brooklyn College has a strong track record of training diverse students in both academics and research. In addition, NCSU will offer a two-day workshop for area high-school teachers. This summer outreach activity will be conducted in conjunction with the Science House, an organization whose mission is to work in partnership with K-12 teachers to increase the use and impact of hands-on learning technologies in the fields of math and science.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）。铁载体，生物体分泌的生物螯合剂，通过络合增加铁的生物利用度的感知环境作用，传统上排除了其他重要的微量金属的参与，主要集中在生物促进铁的溶解和运输。最近的工作表明，铁载体可能参与的生物溶解和吸收的其他环境中重要的微量金属，包括铬，锰，和钴。铁载体可能发挥重要的，可能是特定的，这些其他金属的作用建议的事实，这些金属的铁载体络合物可能具有稳定常数，等于或超过那些三价铁。整个周期表中出现的铁载体-金属结合强度的调色板，加上一些阳离子在氧化态之间穿梭的趋势，表明了丰富但基本上未被探索的环境化学。尽管这些配合物在微量金属循环中的重要性，因此土壤和自然沃茨的初级生产力，在我们的知识中存在显着的差距，其形成机制，结构因素，在解决方案和矿物-水界面的稳定性，以及它们的环境反应性。为了准确描述铁载体在金属地球化学中的复杂作用，需要对这些相互作用有更深入的了解。种子问题包括：铁载体和含铁载体的多配体混合物增溶矿物中痕量金属的效果如何？痕量金属-铁载体复合物在表面和环境相关的水溶液条件下的稳定性如何？金属-铁载体复合物的反应性如何与其他环境相关物质的地球化学循环相耦合？金属-铁载体复合物的结构如何控制其金属选择性？该研究项目将利用复合物形成-降解方法来阐明金属-铁载体复合物的行为：通过铁载体促进金属（氢）氧化物的溶解形成复合物;表征水溶液和吸附的金属-铁载体复合物的稳定性和结构;以及定量复合物与金属氧化物表面的反应性，以及产生这种化学反应的分子尺度结构。现在越来越明显的是，铁载体参与了不同的环境化学，需要更复杂的范例来描述它们对铁以外的痕量金属的地球化学循环的影响。拟议工作的智力价值源于一个新的概念模型的发展，以描述铁载体在环境中发挥的多方面作用。对这些过程的定量分子尺度的理解将阐明铁载体影响微量金属循环的基本机制，并通过地球化学和地球生物学建立这些金属与其他元素之间的联系。拟议工作的更广泛影响超出了地球科学的基本发现，涉及教育、广泛的跨学科科学领域和环境管理。该项目将提供经验，以早期职业生涯的科学家，以及广泛的，多学科的教育，以NCSU研究生和布鲁克林学院的本科生团队。达克沃思帮助在地区大学举办一系列访问研讨会，招收研究生，特别是来自代表性不足的群体。布鲁克林学院在学术和研究方面培养多样化的学生方面有着良好的记录。此外，NCSU将为地区高中教师提供为期两天的讲习班。今年夏季的外展活动将与科学之家一起进行，该组织的使命是与K-12教师合作，增加数学和科学领域动手学习技术的使用和影响。