Novel ultra-high resolution mass spectrometric approaches to decipher structural and physico-chemical drivers of soil organic matter stabilization

新型超高分辨率质谱方法破译土壤有机质稳定的结构和物理化学驱动因素

• 批准号: 465121608
• 负责人: Dr. Oliver Lechtenfeld
• 金额: --
• 依托单位: Max-Planck-Institut für Biogeochemie (MPI-BGC)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/465121608?language=en
• 关键词: Novel; ultra; resolution; mass; spectrometric

Stable soil organic matter (SOM) is an inherent property but also a requirement for soil ecosystem functioning. Microbial activity is a major driver of carbon turnover and SOM formation, but the extent to which stable SOM is formed is modulated by boundary conditions like redox state and mineral composition. Advancement in our understanding of SOM stabilization mechanisms is currently limited by the ability to directly assess the molecular composition of the mineral associated fraction and to determine the molecular structures of SOM, which are ultimately decisive factors for the carbon sequestration in soils. New analytical concepts and methods for chemical high resolution analyses are thus urgently needed. Structure-specific and surface-sensitive FT-ICR MS methods opens up an entirely new perspective to study microbial utilization of substrates and energy-use channels, map transformation pathways, decipher structure-energy relationships in complex SOM, explore the formation and stability of mineral-associated OM, and finally to understand SOM stabilization on a holistic level. To this end, we will employ 1) online-LC-FT-ICR MS to obtain physico-chemical information and LC-tandem MS methods to get meaningful compositional and structural information even for the most complex SOM, 2) functional group enumeration via isotope tagging to study the prevalence of structural moieties on a molecular level even when tandem MS fails to resolve compound classes, and 3) direct LDI-FT-ICR MS for the surface analysis of the organic matter after sorption to minerals. We will apply these tools to microbial microcosm experiments with different substrates and redox conditions, representing variable energy-use channels, to illuminate energy and matter dissipation on a molecular level.The overarching goal of this proposal is to promote the understanding of complex soil organic matter turnover from a bulk and molecular formula level to a structural level. This new level of SOM understanding, together with the project partners in the SPP SoilSystems will allow an integrative and comprehensive assessment and modeling of the energy-use channels and boundary condition limitations of OM turnover in soils. The proposal will contribute to the central Hypothesis of the SPP SoilSystems via long-term assessment of the energy-use channels and Gibbs energy dissipation of substrates during microcosm experiments, unmasking structural drivers of OM stabilization via the microbial pump, and deciphering the effect of redox and mineral boundary-conditions on the matter use and stabilization of carbon.

土壤稳定有机质是土壤生态系统的固有属性，也是土壤生态系统功能的必要条件。微生物活动是碳周转和SOM形成的主要驱动力，但形成稳定SOM的程度受氧化还原状态和矿物成分等边界条件的调节。目前，我们对SOM稳定机制的理解的进展受到直接评估矿物相关部分的分子组成和确定SOM的分子结构的能力的限制，这最终是土壤固碳的决定性因素。因此，迫切需要新的分析概念和方法进行化学高分辨率分析。结构特异性和表面敏感的FT-ICR MS方法开辟了一个全新的视角来研究微生物利用底物和能量利用渠道，映射转化途径，破译复杂SOM中的结构-能量关系，探索矿物相关OM的形成和稳定性，并最终在整体水平上了解SOM的稳定性。 为此，我们将采用1）在线LC-FT-ICR MS获得物理化学信息，并采用LC-串联MS方法获得有意义的组成和结构信息，即使是最复杂的SOM，2）通过同位素标记的官能团计数，即使串联MS无法分辨化合物类别，也可以在分子水平上研究结构部分的普遍性，3）直接LDI-FT-ICR MS用于矿物吸附后有机质的表面分析。我们将这些工具应用于微生物的微观实验与不同的基板和氧化还原条件下，代表可变的能量使用渠道，照亮能量和物质耗散的分子水平上，这个建议的首要目标是促进复杂的土壤有机质周转从散装和分子式水平的结构水平的理解。这一新的SOM理解水平，与SPP SoilSystems的项目合作伙伴一起，将允许对土壤中OM周转的能量使用渠道和边界条件限制进行综合全面的评估和建模。该提案将有助于SPP SoilSystems的中央假说通过长期评估的能量使用渠道和吉布斯能量耗散的基质在微观实验，通过微生物泵揭示OM稳定的结构驱动程序，并破译氧化还原和矿物边界条件对物质的使用和碳的稳定的影响。