Collaborative Research: Unraveling the bacterium-mineral interface - Nanoscale structures and forces

合作研究：揭示细菌-矿物质界面——纳米级结构和力

• 批准号: 0525297
• 负责人: Steven Lower
• 金额: $ 31.91万
• 依托单位: Ohio State University Research Foundation -DO NOT USE
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-10-01 至 2009-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0525297&HistoricalAwards=false
• 关键词: Collaborative; Research; Unraveling; bacterium; mineral

EAR-0525297, Lower, Ohio State University Research FoundationEAR-0525340, Bickmore, Brigham Young UniversityEAR-0525151, Beveridge, University of Guelph Bacteria are the most prolific group of organisms on the Earth in terms of their geographic extent as well as their longevity across geologic time. Most bacteria live by creating habitats on the surface of solid particles such as minerals, which may be located in soil, subsurface, or aquatic environments. Bacteria perceive the presence of mineral surfaces through force "cues", which allow a cell to physically feel another surface. While inter- and intra-molecular forces dominate the lives of microorganisms, their seemingly infinitesimal magnitude and length-scale have made them difficult to study. This proposed research will begin to shed light onto this problem though a unique combination of molecular modeling, force measurements, and microscopic images of well-characterized silica minerals and bacteria that have been genetically modified to produce specific cell wall macromolecules. First, the natural distribution, density, and acid-base reactivity of functional groups on specific faces of phyllosilicate and silicate crystals (and possibly also on the surface of a bacterium) will be determined with atomic force titration measurements. These measurements will be interpreted with a new method for predicting acid-base reactivity of individual functional groups that involves ab initio structure calculations. Second, atomic force microscopy will be used to measure intermolecular forces between wild-type and mutant strains of Pseudomonas aeruginosa and silicate minerals. These force measurements will be interpreted in light of the previously obtained molecular-scale models of the mineral surface acid-base reactivities. The intellectual merit of this proposal is that the combination of molecular models with force measurements will allow an unprecedented view of the fundamental forces or cues that exist at the interface between a living bacterium and mineral surface in situ. This goal will be accomplished through the collective efforts of our interdisciplinary research team that includes scientists specializing in geochemistry, mineralogy and molecular modeling (Bickmore and Lewis), geomicrobiology and nanoscience (Lower and Beveridge), and physical force laws (Dutcher and Israelachvili). The microorganism used in these experiments, P. aeruginosa, is a model Gram negative bacterium. It is ubiquitous in water, soil, and subsurface environments where it lives on the surface of minerals or other particles. It is also a common bacteria species on plants and animals, where it often functions as an opportunistic pathogen. The minerals used in these experiments include silicates, which are the most common inorganic phases on Earth. Probing the interface between P. aeruginosa and silicate minerals will have broader implications and societal benefits that can be applied to issues ranging from the transport of microorganisms in aquifers to the formation of biofilms on solid substrates. Further, this proposal will impact the lives of a number of graduate students and undergraduates. These students will be cross trained in biochemistry, microbiology, geochemistry, and mineralogy, and they will also gain experience with state-of-the-art instruments such as scanning probe microscopes, laser scanning microscopy, and transmission electron microscopy. Finally, this proposal will provide funds to support K-6 outreach programs that are designed to expose young students to the interplay between the biological and physical sciences.

俄亥俄州下区州立大学研究基金会Bickmore，杨百翰大学Bickmore-0525297 Beveridge，圭尔夫大学细菌是地球上最多产的生物群体，就其地理范围以及其在地质时代的寿命而言。 大多数细菌通过在固体颗粒（如矿物质）的表面上创造栖息地而生存，这些固体颗粒可能位于土壤，地下或水生环境中。 细菌通过力“线索”感知矿物表面的存在，这使得细胞能够物理地感受到另一个表面。 虽然分子间和分子内的力主导着微生物的生命，但它们看似微不足道的大小和长度尺度使它们难以研究。 这项拟议中的研究将开始揭示这个问题，通过一个独特的组合分子建模，力测量，以及表征良好的二氧化硅矿物和细菌的显微图像，已被遗传修饰，以产生特定的细胞壁大分子。 首先，将用原子力滴定测量来确定页硅酸盐和硅酸盐晶体的特定表面上（并且还可能在细菌的表面上）的官能团的自然分布、密度和酸碱反应性。 这些测量将解释与一个新的方法，用于预测酸-碱反应的个别官能团，涉及从头计算结构计算。 其次，原子力显微镜将被用来测量铜绿假单胞菌的野生型和突变株和硅酸盐矿物之间的分子间的力量。 这些力的测量将被解释在以前获得的矿物表面酸碱反应性的分子尺度模型。 这一建议的智力价值是，结合分子模型与力的测量将允许一个前所未有的观点的基本力量或线索，存在于一个活的细菌和矿物表面之间的界面原位。 这一目标将通过我们的跨学科研究团队的集体努力来实现，该团队包括专门从事地球化学，矿物学和分子建模（Bickmore和刘易斯），地质微生物学和纳米科学（Lower和Beveridge）以及物理力定律（Dutcher和Israelachvili）的科学家。 这些实验中使用的微生物铜绿假单胞菌是革兰氏阴性菌的模型。 它在水、土壤和地下环境中无处不在，它生活在矿物或其他颗粒的表面。 它也是植物和动物上的常见细菌物种，通常作为机会病原体发挥作用。 这些实验中使用的矿物包括硅酸盐，这是地球上最常见的无机相。 探索铜绿假单胞菌和硅酸盐矿物之间的界面将具有更广泛的意义和社会效益，可应用于从含水层中微生物的运输到固体基质上生物膜的形成等问题。 此外，该提案将影响许多研究生和本科生的生活。 这些学生将在生物化学，微生物学，地球化学和矿物学交叉培训，他们还将获得与国家的最先进的仪器，如扫描探针显微镜，激光扫描显微镜和透射电子显微镜的经验。 最后，这项提案将提供资金，以支持K-6推广计划，旨在使年轻学生接触生物科学和物理科学之间的相互作用。