CAREER: A Triple-Isotope Approach to Unraveling Subsurface Food Webs

职业：揭示地下食物网的三同位素方法

• 批准号: 2042249
• 负责人: Magdalena Osburn
• 金额: $ 76.44万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2042249&HistoricalAwards=false
• 关键词: CAREER; Triple; Isotope; Approach; Unraveling

A vast ecosystem of bacteria and other microorganisms live beneath your feet. This biome extends kilometers deep into the Earth's crust and contains as much organic carbon as surface life. While scientists know a lot about who these microbes are, understanding what they do for a living is a harder question. Ecologists use chemical signatures of plants and animals to map food chains. In this work, Prof. Osburn will develop a new tool to similarly map microbial food webs, focusing on those found 100s to ~10,000 feet underground. Just like the signatures in fingernails distinguish carnivores from vegetarians, this tool will reveal which carbon and nitrogen sources are uses in the shallow vs. ultra-deep places underground. The implications of what subsurface microbes eat are surprisingly global. If they eat mostly organic matter made by surface plants, then they are sequestering carbon in huge amounts and depend on surface ecosystems. If these microbes instead eat and breathe inorganic materials and use CO2, then these ecosystems could be very ancient indeed. The scientific concepts underlying this work (food chains, microbial ecology, earth system science, and field-based inquiry) are well suited to be adapted for high school classrooms. Prof. Osburn will develop activities featuring these concepts in collaboration with Science in Society and Chicago Public Schools, with the ultimate goal of introducing Earth Science and field-based inquiry to students with a diversity of backgrounds and perspectives. She will also host some of these students as interns for immersive laboratory experiences.The continental subsurface harbors vast and active microbial biospheres; however, the net dependence of these microbes on surficial inputs remains unknown. This work will interrogate the dependency of subsurface microbial food webs on surface carbon, within a gradient of subsurface environments (shallow to 2.9 km deep). Ultimately the questions are: Are subsurface ecosystems dependent on surficial inputs, how does this change with depth, and how might it have changed with time? Ultra-deep continental ecosystems may live independently of surficial organic matter and record signatures of dark primary productivity in their biomass. Prof. Osburn will develop a novel amino acid (AA) triple isotope fingerprint and apply it to deconvolve trophic relationships in a range of deep subsurface environments. To accomplish these ends, first she will calibrate the isotopic fingerprint with relevant heterotrophic and chemoautotrophic microbes (Objective 1), then analyze subsurface biomass from three well-characterized localities including shallow (1-150 m), intermediate (250-1500 m), and ultra-deep (2.4-2.9 km) environments (Objective 2). Education and outreach activities center on addressing the grave problem of diversity in Geoscience by building interactive, analytical content modules for diverse Chicago public high school classrooms (Objective 3) and creating immersive laboratory experiences for high school students via internships and field opportunities (Objective 4). By incorporating research products into the K-12 classroom and inviting high school interns into research arenas, she directly links research and education objectives.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.

巨大的细菌和其他微生物生态系统生活在您的脚下。该生物群落延伸到地球的深处，并含有与表面寿命一样多的有机碳。尽管科学家对这些微生物是谁了解很多，但了解他们为谋生而做的事情是一个更困难的问题。生态学家使用动植物的化学特征来绘制食物链。在这项工作中，奥斯本教授将开发一种新工具来类似地绘制微生物食品网，重点是发现100秒至约10,000英尺的地下。就像指甲的签名将食肉动物与素食主义者区分开一样，该工具将揭示哪些碳和氮源在地下的浅层与超深的地方使用。地下微生物的含义令人惊讶地全球化。如果他们主要吃地表植物制造的有机物，那么它们将大量隔离碳，并取决于表面生态系统。如果这些微生物代替进食并呼吸无机材料并使用二氧化碳，那么这些生态系统确实可能非常古老。这项工作的基础科学概念（食物链，微生物生态学，地球系统科学和基于现场的探究）非常适合适用于高中教室。奥斯本教授将与社会和芝加哥公立学校的科学合作开发这些概念的活动，其最终目的是向具有多种背景和观点的学生介绍地球科学和基于现场的探究。她还将接待其中一些学生作为沉浸式实验室经验的实习生。但是，这些微生物对表面输入的净依赖性仍然未知。这项工作将在地下环境的梯度（深到2.9 km）的梯度内询问地下微生物食物网对表面碳的依赖性。最终，问题是：地下生态系统是否取决于表面输入，这会随着深度的变化以及时间如何随着时间而变化？超深的大陆生态系统可以独立于表面有机物和记录其生物量黑暗主要生产力的标志。奥斯本教授将开发一种新型的氨基酸（AA）三相同位素指纹，并将其应用于一系列深层地下环境中的veNVOLD营养关系。为了完成这些目的，首先，她将用相关的异养和化学自动营养的微生物（目标1）校准同位素指纹，然后分析来自三个浅层（1-150 m），中间（250-1500 m）和Ultra-deep（2.4-2.4-2.9 km）的三个良好特征（1-150 m）的三个良好地方（包括1-150 m）的地下生物量。教育和外展活动集中在解决各种芝加哥公立高中教室（目标3）的互动，分析内容模块并通过实习和现场机会为高中生创造沉浸式实验室经验（目标4），从而解决了地球科学多样性的严重问题（目标4）。通过将研究产品纳入K-12教室并邀请高中实习生加入研究领域，她直接联系了研究和教育目标。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估评估标准的评估来支持的。