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

来自冰川和冰盖的冰芯提供了过去环境条件的详细档案，加深了我们对地球气候的理解。南极西部冰盖中的微生物在冰川时期被掩埋，形成了地层记录，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的联系。然而，降落在冰盖上的微生物细胞会受到由于埋葬和与冰中长期隔离相关的条件而改变的栖息地条件的压力。这些过程可能导致微生物细胞地层记录的保真度损失。我们对微生物如何以及是否在冰盖内的冰川-间冰期期间在埋葬中存活并保持活力知之甚少。这项分析将确定可行的和保存的微生物群落以及允许细胞活力的核心基因组适应，这将促进微生物学和冰川学领域的知识，同时提高与过去气候和未来潜在全球气候影响相关的冰芯测量的保真度。这种探索性的奋进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变革性一步。该项目将与波士顿科学博物馆合作，通过教育和宣传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学科研究。该项目的结果将提供第一个基于南极冰盖单细胞全基因组测序的DNA数据，并告知沉积后过程是否影响微生物对古环境条件的解释。确定活的和保存的微生物细胞的分类学身份，并解码赋予埋葬和长期生存能力的遗传库的目标将通过利用来自西南极冰盖分水岭（WD）冰芯的约60，000年历史记录的子样本来实现。WD样本将使用沙漠研究所的冰芯融化系统融化，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细胞分选进行分选，并且单独分选的细胞将对其基因组进行测序。基于荧光的方法将区分活的（代谢活性）细胞与那些非活的但保存在冰中的细胞（含DNA）。基因组分析将确定每个细胞的分类，在永久冷冻环境中赋予生存的已知基因的存在，并比较分析基因组，以确定活细胞在冰盖中持续生存所需的核心基因组。这项工作的成果将扩大生物测量和污染控制的潜力，从存档的冰芯。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.