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

合作研究：利用非定向代谢物在分子水平上表征海洋溶解有机物的微生物转化溶解有机物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，并影响微生物多样性。微生物将一些溶解的有机物质转化为二氧化碳(呼吸作用)，而其他形式的溶解有机物质通过微生物过程改变并持续存在于海洋中。因此，了解微生物如何改变溶解有机物的组成和反应活性是很重要的。该项目将研究溶解有机物的化学结构，以确定：1)满足碳需求的分子(生物质生产减去呼吸损失)和2)微生物活动产生的转化过程。该项目将结合实验室实验和Moorea珊瑚礁长期生态研究现场的实地研究。该项目将支持对三名海洋生物地球化学研究生的培训。本科培训的目的是对代表不足的少数族裔(URM)学生进行持续指导。本科生将从圣地亚哥州立大学和夏威夷大学ʻI at MāNoa的少数族裔服务机构的现有项目中招聘。本科生将参加斯克里普斯海洋研究所面向本科生的冲浪研究经验计划，在那里他们将进行海洋化学研究。其目标是提供一种指导方法，能够成功克服URM参与STEM的障碍，并增加这些学生在海洋科学方面的留存率。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，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学的工具，以确定海洋溶解有机物(DOM)中比目前使用传统方法可能的更大比例的化学结构。该项目将使用串联质谱仪和联网技术将有机化合物全面分类为分子家族，并确定常见的化学转化。然后，使用一个发展良好的基于现场的实验生态系统来产生不同的不稳定的DOM池，研究小组将通过水解酶的表达来跟踪微生物的转化，并测量对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计划内进行的实地调查将探索跟踪环境中特定分子变化的方法，并验证对似乎累积为半不稳定DOM的化合物类的实验观察。通过将实验室和野外实验和海洋调查与非靶向代谢组学分析工具的改进相结合，该项目将表征反应性DOM在海洋中的命运。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.