ANT LIA: Collaborative Research: Genetic Underpinnings of Microbial Interactions in Chemically Stratified Antarctic Lakes

Microbial communities are of more than just a scientific curiosity. Microbes represent the single largest source of evolutionary and biochemical diversity on the planet. They are the major agents for cycling carbon, nitrogen, phosphorus, and other elements through the ecosystem. Despite their importance in ecosystem function, microbes are still generally overlooked in food web models and nutrient cycles. Moreover, microbes do not live in isolation: their growth and metabolism are influenced by complex interactions with other microorganisms. This project will focus on the ecology, activity and roles of microbial communities in Antarctic Lake ecosystems. The team will characterize the genetic underpinnings of microbial interactions and the influence of environmental gradients (e.g. light, nutrients, oxygen, sulfur) and seasons (e.g. summer vs. winter) on microbial networks in Lake Fryxell and Lake Bonney in the Taylor Valley within the McMurdo Dry Valley region. Finally, the project furthers the NSF goals of training new generations of scientists by including undergraduate and graduate students, a postdoctoral researcher and a middle school teacher in both lab and field research activities. This partnership will involve a number of other outreach training activities, including visits to classrooms and community events, participation in social media platforms, and webinars.

Part II: Technical description: Ecosystem function in the extreme Antarctic Dry Valleys ecosystem is dependent on complex biogeochemical interactions between physiochemical environmental factors (e.g. light, nutrients, oxygen, sulfur), time of year (e.g. summer vs. winter) and microbes. Microbial network complexity can vary in relation to specific abiotic factors, which has important implications on the fragility and resilience of ecosystems under threat of environmental change. This project will evaluate the influence of biogeochemical factors on microbial interactions and network complexity in two Antarctic ice-covered lakes. The study will be structured by three main objectives: 1) infer positive and negative interactions from rich spatial and temporal datasets and investigate the influence of biogeochemical gradients on microbial network complexity using a variety of molecular approaches; 2) directly observe interactions among microbial eukaryotes and their partners using flow cytometry, single-cell sorting and microscopy; and 3) develop metabolic models of specific interactions using metagenomics. Outcomes from amplicon sequencing, meta-omics, and single-cell genomic approaches will be integrated to map specific microbial network complexity and define the role of interactions and metabolic activity onto trends in limnological biogeochemistry in different seasons. These studies will be essential to determine the relationship between network complexity and future climate conditions. Undergraduate researchers will be recruited from both an REU program with a track record of attracting underrepresented minorities and two minority-serving institutions. To further increase polar literacy training and educational impacts, the field team will include a teacher as part of a collaboration with the successful NSF-funded PolarTREC program and participation in activities designed for public outreach.

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.

微生物群落绝非仅具科学研究价值。微生物是地球上进化多样性与生化多样性的最主要来源，亦是驱动碳、氮、磷及其他元素在生态系统中循环的核心媒介。尽管微生物对生态系统功能至关重要，但它们在食物网模型与养分循环研究中仍常被忽视。此外，微生物并非孤立生存：其生长与代谢过程会受到与其他微生物间复杂互作的调控。

本项目聚焦南极湖泊生态系统中微生物群落的生态学特征、代谢活性与功能角色。研究团队将解析麦克默多干谷（McMurdo Dry Valley）泰勒谷（Taylor Valley）境内弗莱克瑟尔湖（Lake Fryxell）与邦尼湖（Lake Bonney）中微生物互作的遗传基础，以及环境梯度（如光照、养分、氧气、硫元素）与季节（如夏季与冬季）对微生物网络的影响。

本项目通过吸纳本科生、研究生、博士后研究员与中学教师参与实验室与野外研究工作，助力美国国家科学基金会（NSF, National Science Foundation）培养新一代科研人才的目标落地。该合作还将开展多项外展培训活动，包括校园课堂与社区科普访问、社交媒体参与及网络研讨会等。

第二部分：技术说明

南极极端干谷生态系统的功能，取决于物理化学环境因子（如光照、养分、氧气、硫元素）、季节周期（如夏季与冬季）与微生物之间的复杂生物地球化学互作。微生物网络的复杂度会随特定非生物因子发生变化，这对环境变化威胁下的生态系统脆弱性与恢复力具有重要影响。本项目将评估生物地球化学因子对两座南极冰封湖泊中微生物互作与网络复杂度的影响。

本研究将围绕三大核心目标展开：
1) 基于丰富的时空数据集推断微生物间的正负互作关系，并通过多种分子生物学方法探究生物地球化学梯度对微生物网络复杂度的调控作用；
2) 借助流式细胞术（flow cytometry）、单细胞分选（single-cell sorting）与显微镜技术，直接观测微生物真核生物与其共生伙伴间的互作过程；
3) 利用宏基因组学（metagenomics）构建特定微生物互作的代谢模型。

研究将整合扩增子测序（amplicon sequencing）、泛组学（meta-omics）与单细胞基因组学方法的结果，绘制特定微生物网络的复杂度图谱，并明确微生物互作与代谢活性在不同季节对湖沼生物地球化学趋势的调控作用。上述研究对厘清微生物网络复杂度与未来气候条件之间的关联至关重要。

本项目将从以招收代表性不足少数群体见长的REU（Research Experiences for Undergraduates，本科生科研体验项目）与两所少数族裔服务院校招募本科生科研人员。为进一步提升极地素养培训与教育影响力，野外研究团队将吸纳一名教师参与，该合作依托美国国家科学基金会资助的成熟项目PolarTREC，并将参与面向公众的科普活动。

本资助契合美国国家科学基金会的法定使命，且经基金会以学术价值与社会影响为评审标准的评估后，被认定为值得支持的项目。