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

微生物是海洋碳循环中的重要参与者。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，微生物必须在深海典型的高压(1000米)下工作。尽管已知高压会影响海洋微生物，但它们的碳循环活动大多是在表层海洋压力下测量的。因此，目前尚不清楚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。作为与丹麦和德国科学家合作的结果，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的速率和识别所涉及的微生物是必要的，特别是在深水中。该项目将为不同的本科生和研究生提供培训，以及一名博士后，他们将在美国、丹麦和德国进行海上和实验室的新颖研究。科学家们还将向中学生传授微生物在碳循环中的作用，以及对海洋生命的压力效应。该项目将为高中生提供实习机会，重点是想要上大学的第一代学生。这项工作可能有助于未来识别在高压下发挥良好功能的酶。海洋中随处可见异养微生物(如细菌和古菌)。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度和位置，以及有机物质被保存的程度。尽管研究表明，压力对海洋微生物的活动有深远的影响，但由于专用设备有限，对深海微生物群落的大多数调查都是在大气压下进行的。这项研究将与南丹麦大学丹麦哈达尔研究中心合作，确定压力对微生物群落及其胞外酶的影响，以确定压力对深海和深海压力的影响。在海上和实验室，科学团队将比较减压对深海微生物群落产生的酶活性的影响，以及高压对地表水衍生酶和群落的影响。实地考察工作将在丹麦沿海水域以及开阔的北大西洋和太平洋进行。利用加压系统和原位培养，这项研究将测量多肽和多糖的水解率，这是海洋有机物的两个主要类别。项目活动还将侧重于开发在深海现场测量酶活性的手段。与德国马克斯·普朗克海洋微生物研究所的同事合作，该项目还将研究压力是否会影响自私地摄取多糖。这些研究将提供对未被研究但有助于决定深海有机物命运的关键因素的新见解。该项目由生物和化学海洋学项目资助。该奖项反映了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 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.