Collaborative Research: ANT LIA: Connecting Metagenome Potential to Microbial Function: Investigating Microbial Degradation of Complex Organic Matter Antarctic Benthic Sediments

南极表层海洋沉积物中的微生物在降解有机物和向海洋释放营养物质方面发挥着重要作用。有机物降解是海洋碳循环的中心，提供了有关营养循环、动物食物可获得性和向大气中释放二氧化碳的宝贵信息。这些微生物的功能是通过它们的基因组学来推断的，然而这些方法只解决了可能的功能，而不是它们的实际比率。在这个项目中，PI计划将基因组学方法与酶丰度和活性的细胞估计结合起来，作为确定碳降解速度的一种方法。该项目的目的是在南极洲的几个地区取样，以提供正在研究的过程的大规模图景，并了解微生物群落组成和环境因素，如初级生产力，对微生物活动的重要性。拟议的工作将结合元基因组学、元转录组学和代谢组学等研究工具，结合化学数据和酶分析，确定南极沉积物中有机物的降解情况。该项目有利于国家科学基金会了解南极生物对寒冷和与世隔绝的环境的适应，这对预测气候变化对极地生物的影响至关重要，并有助于我们了解南极生物是如何适应这种环境的。社会将从该项目中受益，教育2名研究生、本科生和K-12学生，并通过在YouTube上分享的短视频制作提高公众素养。PIS建议通过测量几个海洋区域复杂有机物降解的酶和基因功能，促进对极地微生物群落功能的了解，提供对沉积过程的环南极描述。提出了两个假设。第一种假设指出，在整个采样样带的沉积物中，许多降解复杂有机物的基因将是共同的，在基因含量发生变化的地方，反映的是有机质数量和质量的差异，而不是区域差异。第二种假设认为，由于酶的翻译后修饰或快速降解，有机物降解的一小部分基因转录本不会产生可测量的酶活性。PIS将分析在2020年前往南极半岛西部的邮轮中收集的沉积物岩心，并要求参加2023年前往东南极的邮轮。PIS将分析沉积物的代谢组学、转录组学和代谢组学，并结合地球化学数据和酶分析，以确定南极沉积物中复杂有机物的微生物降解。沉积物中有机碳的浓度和含量将用δ13C、δ15N、总有机碳孔隙水荧光法进行测量。结合地理变异性的确定以及对碳源的依赖，这项研究的结果可以为新的假设提供基础，即随着水温的增加，气候变异性如何影响南大洋的地球化学。这一奖项反映了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。

Microbes in Antarctic surface marine sediments have an important role in degrading organic matter and releasing nutrients to the ocean. Organic matter degradation is at the center of the carbon cycle in the ocean, providing valuable information on nutrient recycling, food availability to animals and carbon dioxide release to the atmosphere. The functionality of these microbes has been inferred by their genomics, however these methods only address the possible function, not their actual rates. In this project the PIs plan to combine genomics methods with cellular estimates of enzyme abundance and activity as a way to determine the rates of carbon degradation. This project aims to sample in several regions of Antarctica to provide a large-scale picture of the processes under study and understand the importance of microbial community composition and environmental factors, such as primary productivity, have on microbial activity. The proposed work will combine research tools such as metagenomics, meta-transcriptomics, and metabolomics coupled with chemical data and enzyme assays to establish degradation of organic matter in Antarctic sediments. This project benefits NSFs goals of understanding the adaptation of Antarctic organisms to the cold and isolated environment, critical to predict effects of climate change to polar organisms, as well as contribute to our knowledge of how Antarctic organisms have adapted to this environment. Society will benefit from this project by education of 2 graduate students, undergraduates and K-12 students as well as increase public literacy through short videos production shared in YouTube. The PIs propose to advance understanding of polar microbial community function, by measuring enzyme and gene function of complex organic matter degradation in several ocean regions, providing a circum-Antarctic description of sediment processes. Two hypotheses are proposed. The first hypothesis states that many genes for the degradation of complex organic matter will be shared in sediments throughout a sampling transect and that where variations in gene content occur, it will reflect differences in the quantity and quality of organic matter, not regional variability. The second hypothesis states that a fraction of gene transcripts for organic matter degradation will not result in measurable enzyme activity due to post-translational modification or rapid degradation of the enzymes. The PIs will analyze sediment cores already collected in a 2020 cruise to the western Antarctic Peninsula with the additional request of participating in a cruise in 2023 to East Antarctica. The PIs will analyze sediments for metagenomics, meta-transcriptomics, and metabolomics coupled with geochemical data and enzyme assays to establish microbial degradation of complex organic matter in Antarctic sediments. Organic carbon concentrations and content in sediments will be measured with δ13C, δ15N, TOC porewater fluorescence in bulk organic carbon. Combined with determination of geographical variability as well as dependence on carbon sources, results from this study could provide the basis for new hypotheses on how climate variability, with increased water temperature, affects geochemistry in the Southern 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.