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.

一个巨大的细菌和其他微生物生态系统生活在你的脚下。这个生物群落向地壳深处延伸了数公里，其有机碳含量与地表生物相当。虽然科学家们对这些微生物是谁知道很多，但了解它们的谋生方式是一个更难的问题。生态学家利用植物和动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的工具，以类似的方式绘制微生物食物网，重点关注那些在地下100到10,000英尺的地方发现的微生物。就像指甲中的签名区分食肉动物和素食者一样，这个工具将揭示哪些碳源和氮源在地下浅层和超深层的地方使用。地下微生物吃什么的影响是令人惊讶的全球性的。如果它们主要吃地表植物产生的有机物，那么它们就会吸收大量的碳，并依赖于地表生态系统。如果这些微生物吃和呼吸无机物质并使用二氧化碳，那么这些生态系统可能确实非常古老。这项工作的科学概念（食物链，微生物生态学，地球系统科学和实地调查）非常适合高中课堂。奥斯本教授将与社会科学和芝加哥公立学校合作开发以这些概念为特色的活动，最终目标是向具有不同背景和观点的学生介绍地球科学和实地调查。她还将接待其中一些学生作为实习生，让他们体验身临其境的实验室体验。大陆地下蕴藏着巨大而活跃的微生物生物圈;然而，这些微生物对地表输入的净依赖性仍然未知。这项工作将询问地下微生物食物网对表面碳的依赖性，在地下环境的梯度（浅至2.9公里深）。最终的问题是：地下生态系统是否依赖于地表水输入，这种输入如何随深度变化，以及它如何随时间变化？超深大陆生态系统可能独立于表层有机物而生存，并在其生物量中记录了暗初级生产力的特征。奥斯本教授将开发一种新的氨基酸（AA）三重同位素指纹，并将其应用于解卷积营养关系在一系列深地下环境。为了实现这些目标，她首先将校准同位素指纹与相关的异养和化能自养微生物（目标1），然后分析地下生物量从三个充分表征的地方，包括浅（1-150米），中间（250-1500米），和超深（2.4-2.9公里）的环境（目标2）。教育和外展活动的中心是通过为不同的芝加哥公立高中教室建立互动的分析内容模块（目标3），并通过实习和实地机会（目标4）为高中生创造身临其境的实验室体验，来解决地球科学多样性的严重问题。通过将研究产品纳入K-12课堂并邀请高中实习生进入研究领域，她将研究和教育目标直接联系起来。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。