Collaborative Research: Characterizing microbial transformation of marine DOM at the molecular level using untargeted metabolomic

合作研究：利用非靶向代谢组学在分子水平上表征海洋溶解有机质的微生物转化溶解有机质是全球碳循环的重要组成部分。溶解有机物为生活在海洋中的微生物提供食物和能量，并影响微生物的多样性。微生物将一些溶解的有机物转化为二氧化碳（呼吸作用），而其他形式的溶解有机物被微生物过程改变并在海洋中持续存在。因此，了解微生物如何改变溶解有机物的组成和反应性是很重要的。该项目将检查溶解有机物的化学结构，以确定：1)满足碳需求的分子（生物量产生减去呼吸损失）和2)由微生物活动产生的转化过程。该项目将在Moorea珊瑚礁长期生态研究站进行实验室实验和实地研究。该项目将支持培训三名海洋生物地球化学研究生。本科培训旨在持续指导代表性不足的少数民族（URM）学生。本科生将从圣地亚哥州立大学和夏威夷大学（网址：Mānoa）少数民族服务机构现有的项目中招募。本科生将参加斯克里普斯海洋学研究所SURF本科生研究经验项目，在那里他们将进行海洋化学研究。目标是提供一种指导方法，可以成功地克服URM参与STEM的障碍，并增加这些学生对海洋科学的保留。这项工作将结合现场和实验室研究，使用先进的分子水平化学表征工具来探索细菌如何改变溶解在海水中的有机化合物的组成和生物反应性。此外，该项目将开发基于信息的工具，以识别比目前使用传统方法更大比例的海洋溶解有机物（DOM）化学结构。该项目将使用串联质谱和网络技术对有机化合物进行分子族分类，并确定常见的化学转化。然后，利用一个成熟的野外实验生态系统来产生多种稳定的DOM池，研究团队将通过水解酶的表达来跟踪微生物的转化，并测量特定微生物分类群和代谢的选择。这种方法定义了参与支撑dom -微生物相互作用的碳通量的单个分子和更广泛的化合物类别的反应性。在Moorea珊瑚礁长期生态研究项目中进行的实地调查将探索跟踪环境中特定分子转化的方法，并验证似乎以半不稳定DOM积累的化合物类别的实验观察结果。通过将实验室和现场实验以及海洋调查与非目标代谢组学的分析工具相结合，该项目将描述海洋中活性DOM的命运。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Collaborative Research: Characterizing microbial transformation of marine dissolved organic matter at the molecular level using untargeted metabolomicsDissolved organic matter is an important component of the global carbon cycle. Dissolved organic matter provides food and energy for microbes living in the ocean and influences microbial diversity. Microbes convert some dissolved organic matter to CO2 (respiration) whereas other forms of dissolved organic matter are altered by microbial processes and persist in the ocean. Thus, it is important to understand how microbes change dissolved organic matter composition and reactivity. This project will examine the chemical structure of dissolved organic matter to identify: 1) molecules that fulfill carbon demand (biomass produced minus losses from respiration) and 2) transformation processes that result from microbial activity. The project will combine lab experiments and field studies at the Moorea Coral Reef Long Term Ecological Research site. The project will support training for three graduate students in marine biogeochemistry. Undergraduate training is aimed at sustained mentoring of underrepresented minority (URM) students. Undergraduates will be recruited from existing programs at Minority Serving Institutions at San Diego State University and the University of Hawaiʻi at Mānoa. Undergraduates will participate in the Scripps Institution of Oceanography SURF Research Experiences for Undergraduates program, where they will conduct research in marine chemistry. The goal is to provide a mentoring approach that can successfully overcome roadblocks to URM engagement in STEM and increase retention of these students in marine science.This work will combine field and lab studies using advanced molecular-level chemical characterization tools to explore how bacteria alter the composition and bioreactivity of organic compounds dissolved in seawater. Additionally, this project will develop informatics-based tools to identify a larger proportion of chemical structures in marine dissolved organic matter (DOM) than is currently possible using traditional approaches. The project will use tandem mass spectrometry and networking techniques to comprehensively classify organic compounds into molecular families and determine common chemical transformations. Then, using a well-developed field-based experimental ecosystem to produce diverse labile DOM pools the research team will track microbial transformation using expression of hydrolytic enzymes and measure selection for particular microbial taxa and metabolisms. This approach defines the reactivity of individual molecules and broader compound classes participating in carbon fluxes that underpin DOM-microbe interactions. Field surveys conducted within the Moorea Coral Reef Long Term Ecological Research program will explore methods to track transformation of specific molecules in the environment and validate experimental observations of compound classes that appear to accumulate as semi-labile DOM. By integrating laboratory and field experiments and oceanographic surveys with the refinement of analytical tools for untargeted metabolomics, this project will characterize the fate of reactive DOM in the ocean.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.