Collaborative Research: Importance of Heterotrophic and Phototrophic N2 Fixation in the McMurdo Dry Valleys on Local, Regional and Landscape Scales

合作研究：麦克默多干旱山谷异养和光养固氮对当地、区域和景观尺度的重要性

• 批准号: 1246102
• 负责人: Douglas Capone
• 金额: $ 39.31万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1246102&HistoricalAwards=false
• 关键词: Collaborative; Research; Importance; Heterotrophic; Phototrophic

The McMurdo Dry Valleys in Antarctica are recognized as being the driest, coldest and probably one of the harshest environments on Earth. In addition to the lack of water, the biota in the valleys face a very limited supply of nutrients such as nitrogen compounds - necessary for protein synthesis. The glacial streams of the Dry Valleys have extensive cyanobacterial (blue green algae) mats that are a major source of carbon and nitrogen compounds to biota in this region. While cyanobacteria in streams are important as a source of these compounds, other non-photosynthetic bacteria also contribute a significant fraction (~50%) of fixed nitrogen compounds to valley biota. This research effort will involve an examination of exactly which non-phototrophic bacteria are involved in nitrogen fixation and what environmental factors are responsible for controlling nitrogen fixation by these microbes. This work will resolve the environmental factors that control the activity, abundance and diversity of nitrogen-fixing microbes across four of the McMurdo Dry Valleys. This will allow for comparisons among sites of differing latitude, temperature, elevation and exposure to water. These results will be integrated into a landscape wetness model that will help determine the impact of both cyanobacterial and non-photosynthetic nitrogen fixing microorganisms in this very harsh environment.The Dry Valleys in many ways resemble the Martian environment, and understanding the primitive life and very simple nutrient cycling in the Dry Valleys has relevance for understanding how life might have once existed on other planets. Furthermore, the study of microbes from extreme environments has resulted in numerous biotechnological applications such as the polymerase chain reaction for amplifying DNA and mechanisms for freeze resistance in agricultural crops. Thus, this research should yield insights into how biota survive in extreme environments, and these insights could lead to other commercial applications.

南极洲的麦克默多干谷被认为是地球上最干燥、最寒冷、可能是最恶劣的环境之一。除了缺水，山谷中的生物群还面临着非常有限的营养供应，如氮化合物-蛋白质合成所必需的。干旱山谷的冰川溪流有广泛的蓝藻（蓝绿色藻类）垫，是该地区生物群碳和氮化合物的主要来源。虽然溪流中的蓝细菌是这些化合物的重要来源，但其他非光合细菌也为山谷生物群贡献了相当大一部分（约50%）的固定氮化合物。这项研究工作将涉及检查哪些非光养细菌参与固氮，以及哪些环境因素负责控制这些微生物的固氮。这项工作将解决环境因素，控制活动，丰度和多样性的固氮微生物在四个麦克默多干旱山谷。这将有助于对纬度、温度、海拔和水暴露程度不同的地点进行比较。这些结果将被整合到一个景观湿度模型中，这将有助于确定蓝藻和非光合固氮微生物在这种非常恶劣的环境中的影响。干谷在许多方面与火星环境相似，了解干谷中的原始生命和非常简单的营养循环对于了解其他行星上的生命曾经是如何存在的具有相关性。此外，对来自极端环境的微生物的研究导致了许多生物技术应用，例如用于扩增DNA的聚合酶链式反应和农作物抗冻性的机制。因此，这项研究应该能够深入了解生物群如何在极端环境中生存，这些见解可能会导致其他商业应用。