Collaborative Research: Microbial necromass decomposition: moving from predictions to principles

人们日益认识到，微生物通过其自身的死细胞物质（统称为坏死物质）的输入，是土壤中有机物质积累的重要贡献者。尽管在量化生态因素影响的速度necromass分解，微生物实际上驱动这种营业额和不同的功能群之间的相互作用如何影响降解动力学的进展仍然知之甚少。拟议研究的总体目标是从功能上表征细菌和真菌如何单独和共同降解微生物坏死物质，以及坏死物质中的碳和氮如何进入不同的生态系统池（土壤和植物）。研究团队的跨学科优势将提供一个全面的了解如何分解者社区功能影响微生物necromass分解的方式直接相关的重要生态系统服务，如土壤碳储存和植物养分的获取。沿着我们对与坏死相关的微生物群落的功能的理解，该项目有多个更广泛的影响活动，重点是与公众分享知识，并培训以STEM为重点的学生的多样化池。 具体的研究目标包括：目标1：利用已被充分研究的真菌和细菌分解系统，表征参与微生物坏死物降解的基因和代谢途径;目标2：确定哪些土壤微生物利用来自微生物坏死物的资源，以及其分解如何影响土壤碳库和氮库;目标3：跟踪树木如何通过外生菌根真菌共生获得微生物坏死物来源的氮。这些目标将通过一系列综合实验来实现，这些实验从单个微生物培养物扩展到复杂的群落。在第一个目标中，基于RNAseq的实验室实验将在生态相关和多样化的真菌和细菌中产生真菌坏死块腐烂期间基因表达的详细概况。第二个目标将耦合qSIP分析的微生物群落对基于现场的腐烂necromass与周围的土壤和根的同位素分析（使用IRMS和NanoSIMS成像），以定量跟踪碳和氮的释放从necromass类型到不同的生态系统池。最后，在目标3中，将通过实验操作存在于实验室培养的necommass上的微生物群落，以研究初始基质化学和种间竞争如何影响外生菌根真菌转移到树木的necommass氮的量。总的来说，这项研究旨在将微生物坏死物分解的研究从主要描述性转变为机械预测性科学。该奖项反映了NSF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。

Microorganisms have been increasingly recognized as significant contributors to the accumulation of organic matter in soil through the inputs of their own dead cell material, collectively referred to as necromass. Despite progress in quantifying the ecological factors affecting the rates of necromass decomposition, which microorganisms actually drive this turnover and how interactions among different functional groups affect degradation dynamics remains poorly understood. The overarching objective of the proposed research is to functionally characterize how bacteria and fungi, both alone and together, degrade microbial necromass and how the carbon and nitrogen from necromass moves into different ecosystem pools (both soils and plants). The cross-disciplinary strengths of the research team will provide a holistic understanding of how decomposer community functioning influences microbial necromass decomposition in ways directly relevant to important ecosystem services such as soil carbon storage and plant nutrient acquisition. Along with enhancing our understanding of the functioning of necromass-associated microbial communities, the project has multiple broader impacts activities focused on sharing knowledge with public audiences and training a diverse pool of STEM-focused students. The specific research aims include: Aim 1: Characterize the genes and metabolic pathways involved in microbial necromass degradation using well-studied fungal and bacterial decomposition systems; Aim 2: Determine which soil microbes use resources derived from microbial necromass and how its decomposition affects soil carbon and nitrogen pools; Aim 3: Track how trees acquire microbial necromass-derived nitrogen via ectomycorrhizal fungal symbioses. These aims will be addressed through an integrated set of experiments that scale from individual microbial cultures to complex communities. In the first aim, RNAseq-based lab experiments will generate a detailed profile of gene expression during the decay of fungal necromass in an ecologically relevant and diverse set of fungi and bacteria. The second aim will couple qSIP analyses of the microbial communities on field-based decaying necromass with isotopic analyses of surrounding soils and roots (using both IRMS and NanoSIMS imaging) to quantitatively track carbon and nitrogen release from necromass types into different ecosystem pools. Finally, in Aim 3, microbial communities present on lab-incubated necromass will be experimentally manipulated to examine how initial substrate chemistry and interspecific competition affect the amount of necromass nitrogen transferred to trees by ectomycorrhizal fungi. Collectively, this research seeks to transition the study microbial necromass decomposition from a largely descriptive to a mechanistically predictive science.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.