EAGER: ANT LIA: Persist or Perish: Records of Microbial Survival and Long-term Persistence from the West Antarctic Ice Sheet

冰川和冰盖的冰芯提供了过去环境条件的详细档案，进一步加深了我们对地球气候的了解。南极西部冰盖上的微生物在冰川期被埋藏，形成了地层学记录，为分析地质事件层的顺序和位置提供了机会，并与南半球气候有潜在联系。然而，降落在冰原上的微生物细胞由于埋藏和长期隔离在冰中的相关条件而受到栖息地条件变化的压力。这些过程可能导致微生物细胞的地层记录失去保真度。我们对微生物如何以及是否能在冰期-间冰期期间存活下来并在冰原内存活下来知之甚少。该分析将确定可行和保存的微生物群落和允许细胞生存的核心基因组适应，这将推进微生物学和冰川学领域的知识，同时提高与过去气候和潜在的未来全球气候影响相关的冰芯测量的保真度。这一探索性的努力有可能成为理解地球上最未被充分研究的环境之一的生态学的革命性的一步。该项目将与波士顿科学博物馆合作，通过教育和推广提高公众的科学素养。此外，该项目将支持两名早期职业科学家和两名本科生在微生物学和气候科学的交叉领域进行跨学科研究。该项目的结果将提供首个基于南极冰盖单细胞全基因组测序的DNA数据，并为沉积后过程是否影响微生物对古环境条件的解释提供信息。通过利用南极西部冰原分裂（WD）冰芯约6万年记录的亚样本，确定可存活和保存的微生物细胞的分类特征，并解码在冰川冰中存活和长期生存的遗传库。WD样品将使用沙漠研究所的冰芯融化系统进行融化，该系统针对冰川生物学采样进行了优化。来自融水的微生物细胞将使用荧光激活的细胞分选进行分类，并对单个分选的细胞进行基因组测序。基于荧光的方法将区分有活力（代谢活跃）的细胞和那些没有活力但保存在冰中（含dna）的细胞。基因组分析将确定每个细胞的分类，确定在永久冰冻环境中存活的已知基因的存在，并对基因组进行比较分析，以确定存活细胞在冰盖中生存所需的核心基因集。这项工作的结果将扩大从存档冰芯进行生物测量和污染控制的潜力。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。

Ice cores from glaciers and ice sheets provide detailed archives of past environmental conditions, furthering our understanding of Earth’s climate. Microorganisms in the West Antarctic Ice Sheet are buried over glaciological time and form a stratigraphy record providing the opportunity of analysis of the order and position of layers of geological events, with potential links to Southern Hemisphere climate. However, microbial cells that land on the ice sheet are subject to the stresses of changing habitat conditions due to burial and conditions associated with long-term isolation in ice. These processes may lead to a loss of fidelity within the stratigraphic record of microbial cells. We know little about how and if microorganisms survive burial and remain alive over glacial-interglacial time periods within an ice sheet. This analysis will identify the viable and preserved community of microorganisms and core genomic adaptation that permit cell viability, which will advance knowledge in the areas of microbiology and glaciology while increasing fidelity of ice core measurements relevant to past climate and potential future global climate impacts. This exploratory endeavor has the potential to be a transformative step toward understanding the ecology of one of the most understudied environments on Earth. The project will partner with the Museum of Science, Boston, to increase public scientific literacy via education and outreach. Additionally, this project will support two early-career scientists and two undergraduates in interdisciplinary research at the intersection of microbiology and climate science. Results from this project will provide the first DNA data based on single-cell whole genomic sequencing from the Antarctic Ice Sheet and inform whether post-depositional processes impact the interpretations of paleoenvironmental conditions from microbes. The goals to determine the taxonomic identity of viable and preserved microbial cells, and decode the genetic repertoire that confers survival of burial and long-term viability within glacial ice, will be achieved by utilizing subsamples from a ~60,000 year old record of the West Antarctic Ice Sheet Divide (WD) Ice Core. WD samples will be melted using the Desert Research Institute’s ice core melting system that is optimized for glaciobiological sampling. Microbial cells from the meltwater will be sorted using fluorescence-activated cell sorting, and individually sorted cells will have their genomes sequenced. The fluorescence-based methods will discern the viable (metabolically active) cells from those cells that are non-viable but preserved in the ice (DNA-containing). The genomic analysis will identify the taxonomy of each cell, presence of known genes that confer survival in permanently frozen environments, and comparatively analyze genomes to determine the core set of genes required by viable cells to persist in an ice sheet. The outcomes of this work will expand the potential for biological measurements and contamination control from archived ice cores.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.