Nitrous oxide production by salt marsh sediment fungi: its significance and mechanisms

一氧化二氮是从自然和农业环境中释放的一种强效温室气体和消耗臭氧的物质。沿海湿地是大气中氧化亚氮的最大天然来源之一，其中大部分气体通量归因于沉积物中的微生物过程。在土壤环境中，真菌是产生一氧化二氮的重要贡献者，但在沿海湿地，真菌的作用在很大程度上是未知的。本项目通过分离的真菌培养物和实地收集的盐沼沉积物，在不同的环境条件下，研究未充分研究的真菌在盐沼氧化亚氮生产中的作用。研究结果有望改善未来的气候预测，并指导盐沼栖息地的恢复和管理，以减少一氧化二氮的产生。除了对研究生和本科生进行研究培训外，该项目还将通过与当地动物园的合作，加强对来自不同背景的当地高中生的科学和保护培训。本项目旨在估算真菌对盐沼沉积物氧化亚氮释放的总体贡献，确定不同氧化还原和营养条件下真菌氧化亚氮产生的代谢基础。研究人员将培养从沼泽沉积物中分离出来的真菌，并使用转录谱来揭示控制一氧化二氮产生的关键基因。他们假设，盐沼真菌主要通过硝酸盐或亚硝酸盐的厌氧呼吸产生氧化亚氮。该项目将通过新型15n示踪剂培养和抑制微生物群落的原核（即细菌）或真核（即真菌）成分来限制真菌对氧化亚氮生产的贡献。该项目将提高对微生物真菌如何在缺氧和氧化还原条件的剧烈变化中生存的理解。该项目由生态系统科学和促进竞争研究的既定计划（EPSCoR）共同资助。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。

Nitrous oxide is a potent greenhouse gas and ozone-depleting substance released from natural and agricultural environments. Coastal wetlands are one of the largest natural sources of nitrous oxide to the atmosphere, with most of the gas flux attributed to microbial processes in the sediment. In soil environments, fungi are significant contributors to nitrous oxide production, but in coastal wetlands the role of fungi is largely unknown. This project examines the role of understudied fungi in nitrous oxide production in salt marshes under varying environmental conditions in isolated fungal cultures and field-collected salt marsh sediments. Research findings are expected to improve future climate predictions and guide the restoration and management of salt marsh habitats to reduce nitrous oxide production. In addition to research training graduate and undergraduate students, this project will enhance scientific and conservation training to local high school students from diverse backgrounds through a partnership with a local zoo. This project aims to estimate the overall contribution of fungi to nitrous oxide release from salt marsh sediments and determine the metabolic basis for fungal nitrous oxide production under different oxidation-reduction and nutrient conditions. The researchers will cultivate fungi isolated from marsh sediments and use transcriptional profiling to reveal key genes that control nitrous oxide production. They hypothesize that salt marsh fungi produce nitrous oxide primarily by the anaerobic respiration of nitrate or nitrite. The project will constrain the contribution of fungi to nitrous oxide production with novel 15N-tracer incubations and inhibition of either the prokaryotic (i.e., bacteria) or the eukaryotic (i.e., fungi) components of the microbial community. This project will improve understanding of how microbial fungi survive the absence of oxygen and drastic daily changes in oxidation-reduction conditions.This project is jointly funded by Ecosystem Science and the Established Program to Stimulate Competitive Research (EPSCoR).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.