Role of fungal denitrification in N2O fluxes from soils

真菌反硝化作用在土壤 N2O 通量中的作用

• 批准号: 251282570
• 负责人: Professor Dr. Marcus A. Horn
• 金额: --
• 依托单位: Institut für Mikrobiologie (ifmb)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/251282570?language=en
• 关键词: Role; fungal; denitrification; N2O; fluxes

The greenhouse gas N2O (nitrous oxide) is produced during denitrification under anoxic conditions in soil. Complete denitrification is the sequential reduction of nitrate via nitrite, nitric oxide and N2O to dinitrogen (N2) and catalyzed by Bacteria as well as fungi. While many bacteria are capable of reducing N2O to N2, most fungi are not. Thus, a substantial contribution of fungi to N2O emission via denitrification from soil is to be anticipated. However, the contribution of fungi to denitrification relative to that of bacteria is not yet sufficiently investigated and precise methods to differentiate between N2O fluxes from bacteria and fungi are lacking to date. Indeed, the development of suitable methods is complicated by the fact that besides denitrification several other N2O forming processes can occur simultaneously in soil. Thus, we developed and evaluated stable isotope (“isotopomer endmember mixing”, IEM) and microbiological (fungal denitrifier gene expression by qPCR) methods to identify and quantify fungal N2O production during the first phase of our project. In the proposed second phase of the project, we will continue method development and use the new developed along with established methods to study the regulation of fungal denitrification as a basis to predict this process to provide a basis for developing measures to mitigate soil N2O fluxes. Our specific objectives are to:1. Evaluate and improve methods to quantify and/or identify the contribution of fungi to soil-derived N2O fluxes2. Quantify the contribution of fungi to soil-derived N2O fluxes with improved methods3. Unravel the control of fungal denitrification and interaction with other N2O and N2 pathways4. Identify fungal key players and their regulation5.Develop and test algorithms of fungal denitrification for biogeochemical models.The work program will be jointly accomplished by two teams hosted at the Thünen Institute in Braunschweig and the Leibniz University Hannover (LUH). The Thünen work program will evaluate and improve inhibitor and stable isotope approaches to quantify fungal denitrification and use those in controlled soil incubations under conditions favouring fungal or bacterial denitrification. The LUH work program will extend quantitative PCR based gene expression targeting only a narrow range of single marker genes to quantitative transcriptomics addressing a broad range of marker genes and thus to develop efficient methods to investigate fungal denitrifier gene expression (FDGE). Stable isotope and FDGE approaches will be jointly used in further soil incubation experiments to study regulation of fungal denitrification and its importance for N2O fluxes in soil. Results will serve to derive control factors that will be used to model fungal denitrification.

温室气体N2O(一氧化二氮)是在土壤缺氧条件下进行反硝化作用时产生的。完全反硝化是在细菌和真菌的催化下，硝酸盐通过亚硝酸盐、一氧化氮和N2O依次还原为氮(N_2)的过程。虽然许多细菌能够将N2O还原为氮气，但大多数真菌不能。因此，真菌通过土壤的反硝化作用对N2O的排放有很大的贡献是可以预期的。然而，相对于细菌，真菌对反硝化的贡献还没有得到充分的研究，而且到目前为止，还缺乏区分细菌和真菌N2O通量的准确方法。事实上，除了反硝化作用外，土壤中还可以同时发生几个其他N2O形成过程，这使得开发合适的方法变得复杂。因此，在我们项目的第一阶段，我们开发并评估了稳定的同位素(“同位素末端成员混合”，IEM)和微生物学(真菌反硝化子基因的qPCR表达)方法来鉴定和定量真菌N2O的产生。在拟议的第二阶段项目中，我们将继续开发方法，并使用新开发的方法和现有的方法来研究真菌反硝化的规律，作为预测这一过程的基础，为制定缓解土壤N2O通量的措施提供依据。我们的具体目标是：1.评估和改进量化和/或确定真菌对土壤来源的N2O通量的贡献的方法。用改进的方法量化真菌对土壤来源的N2O通量的贡献3。揭示真菌反硝化的控制以及与其他N2O和N2途径的相互作用4。确定真菌的关键因素及其调控。5.为生物地球化学模型开发和测试真菌反硝化的算法。该工作计划将由布伦施韦格的Thünen研究所和汉诺威莱布尼茨大学(LUH)的两个团队联合完成。Thünen工作计划将评估和改进量化真菌反硝化的抑制剂和稳定同位素方法，并在有利于真菌或细菌反硝化的条件下，在受控土壤培养中使用这些方法。LUH工作计划将把仅针对小范围单一标记基因的基于定量PCR的基因表达扩展到针对广泛标记基因的定量转录，从而开发研究真菌反硝化基因表达(FDGE)的有效方法。稳定同位素和FDGE方法将在进一步的土壤培养实验中联合使用，以研究真菌反硝化的规律及其对土壤N2O通量的重要性。研究结果将有助于得出用于模拟真菌反硝化作用的控制因子。