Collaborative Research: Influence of phosphorus deficiency on enigmatic biological methane production in oxic freshwater lakes

合作研究：缺磷对含氧淡水湖神秘生物甲烷生产的影响

• 批准号: 1951002
• 负责人: Matthew Church
• 金额: $ 48.59万
• 依托单位: University of Montana
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1951002&HistoricalAwards=false
• 关键词: Collaborative; Research; Influence; phosphorus; deficiency

Atmospheric levels of methane have risen 150% since the Industrial Revolution, and continue to increase. Although energy sector and agricultural sources are major contributors, natural microbiological sources account for roughly half of total global methane emissions. Microbial methane production has long been assumed to be an anoxic process, carried out only under conditions of extremely low to zero oxygen. Recent research has demonstrated the potential for microbial methane production to occur in oxygenated upper waters of lakes and oceans through a previously unappreciated metabolic pathway present in microorganisms. Under conditions of phosphorus deficiency, certain bacteria can utilize otherwise unreactive organic molecules known as methylphosphonates to meet their phosphorus requirements, releasing methane in the process. The extent to which this mechanism supports the out-gassing of methane from lakes to the atmosphere is unknown, as are the consequences of changing environmental conditions upon it. This project will address this knowledge gap by investigating the distributions, rates of and controls on aerobic methane production in Flathead Lake and 18 other Montana lakes of varying phosphorus deficiency status. Because atmospheric deposition of pollutant nitrogen and deliberate measures to curtail phosphorus inputs to lakes can both lead to phosphorus deficiency, it is crucial that we know whether these factors may have the unexpected consequence of enhancing methane emissions. This research will also directly support the education, field and laboratory experiences of graduate and undergraduate students and will provide training to local high school teachers from Native American (Kootenai and Salish) tribal lands.This project will evaluate temporal and spatial variability in microbially-mediated, oxic methane production across lakes with varying phosphorus availability in western Montana. It is guided by the overarching hypothesis: diffusive effluxes of methane from oxic freshwater lakes are directly influenced by the nature and severity of ecosystem nutrient (nitrogen, phosphorus) deficiencies. A combination of observational and experimental approaches employing chemical, stable isotopic, metagenomic and PCR-based gene analyses will be used to examine: 1) time and space variability in the concentration, stable isotope composition, and net production of methane in freshwater lakes in Montana, focusing on Flathead Lake; 2) The extent to which microbial methylphosphonate degradation results in net production of methane in these lakes; 3) The functional diversity, abundances, and transcriptional activities of microorganisms involved in both phosphonate and methane cycling; and 4) How the stoichiometry (specifically nitrogen:phosphorus ratios) of aquatic nutrient (inorganic and total) pools influences oxic methane production and expression of methane cycling functional genes. The study will provide a systematic evaluation of microbial methane sources and the potential contribution of methylphosphonate degradation as a source of methane in oxic freshwater lakes. Results from this project will provide new insights and advance current understanding of coupled interactions between carbon and phosphorus cycling in freshwater lake habitats.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.

自工业革命以来，大气中的甲烷含量已上升 150%，并且还在继续增加。 尽管能源部门和农业来源是主要贡献者，但自然微生物来源约占全球甲烷排放总量的一半。 长期以来，微生物甲烷生产一直被认为是一个缺氧过程，仅在极低至零氧的条件下进行。最近的研究表明，通过微生物中存在的以前未被认识到的代谢途径，微生物在湖泊和海洋的含氧上层水域产生甲烷的潜力。 在缺磷的条件下，某些细菌可以利用其他不反应的有机分子（称为甲基膦酸盐）来满足其对磷的需求，并在此过程中释放甲烷。 这种机制在多大程度上支持甲烷从湖泊释放到大气中，以及环境条件变化对其产生的后果尚不清楚。 该项目将通过调查弗拉特黑德湖和蒙大拿州其他 18 个不同缺磷状况湖泊的需氧甲烷产生的分布、速率和控制来解决这一知识差距。 由于污染物氮的大气沉降和刻意减少磷输入湖泊的措施都可能导致磷缺乏，因此了解这些因素是否可能产生增加甲烷排放的意外后果至关重要。 这项研究还将直接支持研究生和本科生的教育、现场和实验室经验，并将为来自美洲原住民（库特奈和萨利什）部落土地的当地高中教师提供培训。该项目将评估微生物介导的时间和空间变异性，蒙大拿州西部磷可用性不同的湖泊中含氧甲烷的产量。它以总体假设为指导：含氧淡水湖的甲烷扩散流出直接受到生态系统养分（氮、磷）缺乏的性质和严重程度的影响。将采用化学、稳定同位素、宏基因组和基于 PCR 的基因分析的观测和实验方法相结合来检查：1）蒙大拿州淡水湖中甲烷浓度、稳定同位素组成和净产量的时间和空间变化，聚焦弗拉特黑德湖； 2) 微生物甲基膦酸酯降解导致这些湖泊中甲烷净产生的程度； 3）参与磷酸盐和甲烷循环的微生物的功能多样性、丰度和转录活性； 4) 水生营养物（无机和总）库的化学计量（特别是氮：磷比率）如何影响含氧甲烷的产生和甲烷循环功能基因的表达。该研究将对微生物甲烷来源以及磷酸甲酯降解作为含氧淡水湖甲烷来源的潜在贡献进行系统评估。该项目的结果将提供新的见解，并增进目前对淡水湖泊栖息地碳和磷循环之间耦合相互作用的理解。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Productivity and photophysiology in a large, oligotrophic lake

大型贫营养湖的生产力和光生理学

• 发表时间: 2023
• 期刊: Association for the Sciences of Limnology and Oceanography
• 作者: Evans, Kate A.;Tappenbeck, Tyler;Peoples, Logan;Church, Matthew
• 通讯作者: Church, Matthew

Mixing‐driven changes in distributions and abundances of planktonic microorganisms in a large, oligotrophic lake

混合驱动大型贫营养湖中浮游微生物分布和丰度的变化

• DOI: 10.1002/lno.12509
• 发表时间: 2024
• 期刊: Limnology and Oceanography
• 影响因子: 4.5
• 作者: Evans, Kate A.;Peoples, Logan M.;Ranieri, John R.;Wear, Emma K.;Church, Matthew J.
• 通讯作者: Church, Matthew J.