Collaborative Research: Microdiversity drives ecosystem function: SAR11 bacteria as models for oceanic nitrogen loss

该项目研究低氧可用性如何影响SAR11细菌的生物多样性和生态作用，SAR11细菌是海洋中最丰富的微生物群之一。这项工作包括在东热带北太平洋的一系列氧气和营养水平上进行海洋学采样。该研究结合了基因组学、微生物学和生物地球化学方法，确定了SAR11菌株分化为不同的生态位和物种并对生态系统做出生物化学贡献的机制，可能是通过从海水中去除氮。该项目装备下一代研究人员和教育工作者，特别是那些来自代表性不足的少数群体的研究人员和教育工作者，使他们能够利用海洋学、基因组学和微生物学概念来应对当代科学挑战。这一目标是通过结合针对波多黎各大学系统本科生的生物信息学讲习班、中学教师培训讲习班和在研究者实验室的初中或高中教师实习来实现的。这一多方面的研究和教育议程填补了我们对海洋生物多样性理解的空白，确定了SAR11细菌对低氧海洋中营养和碳循环的贡献，并为研究其他生态系统中的微生物过程提供了经验教训和分析工具。这个项目有两个目的。目的1采用比较宏基因组学和单细胞基因组学分析来鉴定将SAR11进化支与低氧区区分开来的代谢特性，以及进化支之间的选择过程或基因流。目的2结合微生物转录组学、同位素示踪剂培养实验和培养，确定确定每个SAR11进化枝生态位空间的氧气和营养条件，并将SAR11基因转录与群落生化结果（包括反硝化导致的氮损失）联系起来。这些目标的成果和用于探测微生物微多样性的信息学方法通过以基因组学为重点的本科讲习班和新的教师培训教育模块传播，包括以实验室为基础的模块，重点关注海洋环境变化下微生物的重要性。这个项目的数据、手稿和信息学工作流程都是公开的。这些结果对于解决在海洋中创造和维持微生物多样性的过程以及为预测多样性如何影响生态系统过程的生物地球化学模型提供信息至关重要。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。

This project studies how low oxygen availability influences the biodiversity and ecological role of SAR11 bacteria, one of the most abundant microbial groups in the ocean. The work involves oceanographic sampling across a range of oxygen and nutrient levels in the Eastern Tropical North Pacific Ocean. Using a combination of genomic, microbiological, and biogeochemical methods, the study identifies the mechanisms by which SAR11 strains diversify into separate niches and species and contribute biochemically to the ecosystem, likely through removing nitrogen from seawater. The project equips the next generation of researchers and educators, notably those from underrepresented minority groups, to use oceanographic, genomic, and microbiological concepts to meet contemporary scientific challenges. This goal is met through a combination of bioinformatic workshops that target undergraduate students from the University System of Puerto Rico, middle school teacher-training workshops, and middle or high school teacher internships in the investigator’s labs. This multifaceted research and educational agenda fills a gap in our understanding of marine biological diversity, identifies the contribution of SAR11 bacteria to nutrient and carbon cycles in low oxygen oceans, and provides lessons and analytical tools to study microbial processes in other ecosystems.This project has two aims. Aim 1 employs comparative metagenomic and single-cell genomic analyses to identify metabolic properties that distinguish SAR11 clades from low oxygen regions and processes of selection or gene flow operating across the clades. Aim 2 combines microbial transcriptomics, incubation experiments with isotope tracers, and culturing to delimit the oxygen and nutrient conditions that define the niche space of each SAR11 clade and to correlate SAR11 gene transcription with community biochemical outcomes, including nitrogen loss through denitrification. The results of these aims and the informatic methods used to probe microbial microdiversity are disseminated through genomics-focused undergraduate workshops, and new teacher-training educational modules, including lab-based modules focused on the importance of microorganisms under environmental change in the oceans. Data, manuscripts, and informatics workflows from this project are made publicly available. The results are critical for resolving the processes that create and sustain microbial diversity in the oceans and informing biogeochemical models that predict how diversity influences ecosystem processes.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.