Collaborative Research: Pressure effects on microbially-catalyzed organic matter degradation in the deep ocean

微生物是海洋碳循环的重要参与者。这些生物在海洋系统中消耗有机碳并产生二氧化碳。由于海洋的平均深度为4000米，微生物必须在深海（1000米）的高压下工作。虽然已知高压会影响海洋微生物，但它们的碳循环活动主要是在海洋表面压力下测量的。因此，这些测量结果在多大程度上反映了深海微生物在高压下的活动仍然是未知的。由于与丹麦和德国的科学家合作，该项目将能够使用特殊设备来调查高压对海洋微生物及其碳循环活动的影响。这项工作对于量化碳循环速率和识别涉及的微生物是必要的，特别是在深水中。该项目将为不同类型的本科生和研究生以及一名将在美国、丹麦和德国进行海上和实验室新研究的博士后提供培训。科学家们还将向中学生讲授微生物在碳循环中的作用以及压力对海洋生物的影响。该项目将为高中生提供实习机会，重点是想上大学的第一代学生。这项工作可能有助于未来努力识别在高压下功能良好的酶。异养微生物（如细菌和古生菌）遍布海洋。它们的生物地球化学功能有助于确定碳和营养物质再生的速率和位置，以及有机物保存的程度。尽管研究表明压力深刻地影响海洋微生物的活动，但由于专用设备的有限可用性，大多数深海微生物群落的调查都是在大气压下进行的。在与南丹麦大学的丹麦哈达尔研究中心的合作下，这项研究将确定压力对微生物群落及其细胞外酶的影响，这些酶具有水浴和深海的压力特征。在海上和实验室中，科学小组将比较减压对深海微生物群落产生的酶的活动的影响，以及高压对地表水衍生的酶和群落的影响。实地考察将在丹麦沿海水域以及北大西洋和太平洋公海进行。利用加压系统和原位孵育，本研究将测量多肽和多糖的水解率，这是两种主要的海洋有机物。项目活动还将侧重于发展在深海中就地测量酶活性的手段。在与德国马克斯·普朗克海洋微生物研究所的同事合作下，该项目还将研究压力是否会影响多糖的自我摄取。这些研究将为未被充分研究的关键因素提供新的见解，这些因素有助于决定深海有机物的命运。本项目由生物和化学海洋学计划资助。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。

Microbes are important players in the carbon cycle in the ocean. These organisms consume organic carbon and produce carbon dioxide in marine systems. Because the average depth of the ocean is 4000 m, microbes must work at high pressures typical of the deep ocean (1000 m). Although high pressure is known to affect marine microbes, their carbon cycling activities have mostly been measured at surface ocean pressures. As a result, it remains unknown how closely these measurements reflect the activities of deep-sea microbes at high pressures. As a result of collaborations with scientists in Denmark and Germany, this project will be able to use special equipment to investigate the effects of high pressures on marine microbes and their carbon cycling activities. This work is necessary to quantify rates of carbon cycling and identify the microbes involved, especially in deep waters. The project will provide training for diverse undergraduate and graduate students, and a postdoc who will conduct novel research in the U.S., Denmark, and Germany, both at sea and in the lab. The scientists will also teach middle school students about the role of microbes in the carbon cycle and pressure effects on life in the ocean. The project will provide internships for high school students, focusing on first-generation students who would like to go to college. This work may aid in future efforts to identify enzymes that function well under high pressure. Heterotrophic microbes (e.g., bacteria and archaea) are found throughout the ocean. Their biogeochemical functions help determine the rates and locations at which carbon and nutrients are regenerated, as well as the extent to which organic matter is preserved. Although research has shown that pressure profoundly affects the activities of marine microbes, most investigations of microbial communities of the deep sea are conducted at atmospheric pressure, due to the limited availability of specialized equipment. In collaboration with the Danish Center for Hadal Research at the University of Southern Denmark, this study will identify the effects of pressure on microbial communities and their extracellular enzymes of pressures characteristic of bathy- and abyssopelagic depths. At sea and in the lab, the scientific team will compare the effects of depressurization on the activities of enzymes produced by microbial communities of the deep ocean, as well as the effects of high pressure on surface-water derived enzymes and communities. Fieldwork will take place in Danish coastal waters, well as in the open North Atlantic and Pacific Oceans. Using pressurization systems and in situ incubations, this study will measure hydrolysis rates of peptides and polysaccharides, two of the major classes of marine organic matter. Project activities will also focus on developing the means to measure enzyme activities in situ in the deep ocean. In collaboration with colleagues from the Max Planck Institute for Marine Microbiology in Germany, this proect will additionally investigate whether pressure affects the selfish uptake of polysaccharides. These studies will provide new insight into understudied but key factors that help determine the fate of organic matter in the deep ocean.This project is funded by the Biological and Chemical Oceanography Programs.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.