Collaborative Research: NSF OCE-BSF: Coupling organic nutrient cycling to methane production in the oligotrophic North Pacific Ocean

合作研究：NSF OCE-BSF：将有机养分循环与贫营养北太平洋甲烷生产耦合

• 批准号: 2241668
• 负责人: Oscar Sosa
• 金额: $ 41.05万
• 依托单位: University of Puget Sound
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2241668&HistoricalAwards=false
• 关键词: Collaborative; Research; NSF; OCE; BSF

Open ocean surface waters are natural sources of methane to the atmosphere. As recently as a decade ago the source of this methane was a mystery, because methane production was only known to occur in certain environments without oxygen. Recently, the discovery of several metabolic pathways that enable microbes to transform organic matter into methane in the presence of oxygen has led to a shift away from the idea that methane can only be produced in anaerobic (oxygen-free) environments. The investigators propose that the pathway microbes use to make methane depends on the nutrient conditions that prevail in open ocean surface waters. In the North Atlantic Ocean, phosphorus limits microbial production, and microbes produce methane as a by-product of getting the phosphorus they need from organic compounds that contain phosphorus. In contrast, nitrogen limits microbial production in the North Pacific Ocean. The team proposes that in the North Pacific Ocean microbes produce methane as a by-product of organic nitrogen degradation. To test this hypothesis, they propose to compare the results of geochemical and biological measurements previously made in the North Atlantic with a parallel set of geochemical measurements they propose to make in the North Pacific Ocean. The award will support collaborations between an early career professor at a primarily undergraduate institution (PUI) and a senior scientist, and between US and Israeli scientists. Undergraduate students will participate in interdisciplinary research spanning oceanography, isotope biogeochemistry, and genome science and will conduct research at sea. The microbiology and genomic research will be integrated into course-based undergraduate research experiences at the University of Puget Sound enabling diverse students to participate directly in authentic research. Results will also be integrated into a graduate level course in marine organic geochemistry available on-line through the MIT Open Courseware website. This is a project jointly funded by the National Science Foundation’s Directorate of Geosciences (NSF-GEO) and the Israel Binational Science Foundation (BSF) in accord with the language in the Memorandum of Understanding between the NSF and the BSF. This Agreement allows a single collaborative proposal, involving US and Israeli investigators, to be submitted and peer-reviewed by NSF. Upon successful results of the NSF merit review and recommendation by the cognizant NSF Program of an award, each Agency funds the proportion of the budget and the investigators associated with its own country.The guiding hypothesis of this study is that although surface seawater in the North Atlantic and North Pacific Subtropical Gyres are both sources of methane to the atmosphere, the underlying microbial processes that produce methane in the two basins are fundamentally different. Microbial production in the Sargasso Sea is chronically phosphorus-limited. To mitigate this limitation, some microbes degrade methylphosphonate that is incorporated into the high molecular weight fraction of dissolved organic matter (HMWDOM) into methane and phosphaote. Bacteria expressing the carbon-phosphorus (C-P) lyase enzyme pathway for phosphonate catabolism dominate the Sargasso Sea microbial community and mediate this form of methane production making it the principal route through which excess methane is produced in the Sargasso Sea. In contrast, microbial production in the North Pacific Subtropical Gyre (NPSG) is chronically nitrogen limited and the proposal postulates that nitrogen acquisition through the degradation of methylamines in HMWDOM is a major route through which excess methane is produced. Methylamines are twenty-fold more abundant than methylphosphonate in marine HMWDOM and the aminotransferase gene linked to the conversion of methylamine into methane in freshwater lakes has closely related sequences in marine bacterial genomes. These sequences are abundant and widespread in marine metagenomes. Although the cycling of methylphosphonate and methylamine in oligotrophic surface waters both produce methane, the study postulates that the two processes will yield methane with distinct and characteristic carbon isotopic values. To test this hypothesis, the team will measure the stable carbon isotope value of the methane produced from HMWDOM methylamine and methylphosphonate. The team will also conduct laboratory experiments that test the capacity of diverse oligotrophic and copiotrophic marine bacterial isolates to convert HMWDOM methylamines to methane. This objective is complemented by a field study in the NPSG northwards from Hawaii along 158°W, the longitude of Station ALOHA, to 25-28°N to conduct geochemical and biological measurements associated with each methane production pathway. The team will obtain water column profiles of methane and ethylene concentration (two products of C-P lyase), methane carbon isotopes, and concentrations and carbon isotope values of HMWDOM methylamine and methylphosphonate. The investigators will quantify the rates of methane production from methylamine and methylphosphonate using stable carbon isotope tracers, C-P lyase activity, and the ratio of C-P lyase to aminotransferase gene abundance and expression in the NPSG. Lastly, the team will compare the bioavailability of HMWDOM methylamine and methylphosphonate to natural microbial communities in the NPSG using a metatranscriptomics approach to examine changes in microbial metabolic functions in response to HMWDOM additions. Together, these data will resolve the relative contribution of the methylamine and methylphosphonate pathways to aerobic methane production in the NPSG and the microbial groups and ecosystem properties underlying methane production. Through this interdisciplinary approach, the study will enhance our understanding of processes controlling aerobic methane production in the environment.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.

开海地表水是大气中甲烷的天然来源。就在十年前，这种甲烷的来源是一种神秘的，因为甲烷的产生仅在没有氧气的某些环境中发生。最近，发现几种代谢途径，使微生物在氧气存在下将有机物转化为甲烷的发现导致人们从甲烷只能在无氧（无氧）环境中产生甲烷的观念转变。研究人员建议，途径微生物用来使甲烷制造甲烷取决于在开海地表水中盛行的养分条件。在北大西洋，磷限制了微生物的产生，微生物产生甲烷作为从含有磷的有机化合物中获得所需的磷的副产品。相反，氮限制了北太平洋的微生物产生。团队提出的，在北太平洋微生物中产生甲烷作为有机氮降解的副产品。为了检验这一假设，他们建议比较先前在北大西洋进行的地球化学和生物学测量结果与他们建议在北太平洋中进行的一系列地球化学测量结果。该奖项将支持小学本科机构（PUI）的早期职业教授与我们与以色列科学家之间的合作。本科生将参加跨学科研究，这些研究涵盖海洋学，同位素生物地球化学和基因组科学，并将在海上进行研究。微生物学和基因组研究将纳入普吉特大学的基于课程的本科研究经验，使潜水员能够直接参与真实的研究。结果还将集成到研究生中。 MIT Open Courseware网站上可在线提供海洋有机地球化学的水平课程。这是一个由国家科学基金会地球科学局（NSF-GEO）和以色列双原则科学基金会（BSF）共同资助的项目，该项目符合NSF与BSF之间的理解备忘录中的语言。该协议允许NSF提交和同行评审的单一协作提案，涉及我们和以色列调查员。根据NSF奖学金计划的NSF值得审查和建议的成功结果，每个机构为预算的比例和与其国家 /国家相关的调查人员提供了资金。这项研究的指导假设是，尽管北大西洋和北太平洋的北太平洋亚型副孔的表面是甲烷对大气层的来源，但在两个甲烷上都是hassey histere ece neperse的，这都是甲烷的基础。萨尔加索海的微生物生产长期不同。为了减轻这种限制，一些微生物降解甲基膦酸盐，这些微生物被掺入溶解有机物（HMWDOR）的高分子重量分数中。表达碳磷（C-P）裂解酶酶途径的细菌占主导地位的Sargasso Sea微生物群落，并介导这种形式的甲烷产生，使其成为Sargasso Sea中多余的甲烷产生的主要途径。相比之下，北太平洋亚热带回旋（NPSG）中的微生物产生是长期的氮有限的，该提议假设通过HMWDOM中甲基胺通过降解而获得氮的含氮是产生过量甲烷的主要途径。在海洋hmwdom中，甲胺比甲基膦酸酯更丰富，在淡水湖中，与甲胺转化为甲胺转化为甲胺的氨基转移酶基因在海洋细菌基因组中具有密切相关的序列。这些序列在海洋宏基因组中很丰富且宽度。尽管在无物表面水中甲基膦酸酯和甲胺的循环均可产生甲基甲烷，但该研究假设这两个过程将产生具有独特和特征性碳同位素值的甲基甲烷。为了检验这一假设，小组将测量由HMWDOM甲胺和甲基膦酸酯产生的甲基的稳定碳同位素值。该团队还将进行实验室实验，以测试潜水贫营养和共生的海洋细菌分离株的能力，以将HMWDOM甲胺转化为甲基磷酸甲酯。该目标是由从夏威夷向北的NPSG沿158°W（Aloha站的经度）向北进行的现场研究完成的，以进行25-28°N，以进行与每种甲烷生产途径相关的地球化学和生物学测量。该团队将获得甲基和乙烯浓度（两种C-P裂解酶产物），甲基碳同位素以及HMWDOM甲胺和甲基膦酸甲酯的浓度和碳同位素值的水柱谱。研究者将使用稳定的碳同位素示踪剂，C-P裂解酶活性以及C-P裂解酶与氨基转移酶基因的基因和表达在NPSG中量化甲胺和膦酸甲酯甲基产生的速率。最后，该团队将使用元文字分组组学方法来比较NPSG中HMWDOM甲胺和甲基膦酸酯与天然微生物群落的生物利用度，以检查对HMWDOM添加的响应，以检查微生物代谢功能的变化。总之，这些数据将解决NPSG中甲基胺和甲基膦酸酯途径对有氧甲基甲烷产生的相对贡献，以及甲基甲烷产生的基于的微生物基团和生态系统特性的相对贡献。通过这种跨学科的方法，该研究将增强我们对环境中有氧甲基甲烷产生的过程的理解。该奖项反映了NSF的法定任务，并通过使用基金会的智力优点和更广泛的影响评估标准来评估NSF的法定任务。