Carbon and energy flow in the soil microbiome – functional groups, activity and interactions in trophic networks

土壤生态系统由碳(C)、养分和能量流驱动，这些都是生物地球化学循环所必需的。特别是，土壤微生物群中的有机体正在引导这些通量。然而，很少有人尝试将动物群食草动物的微生物特征和功能群与热量和二氧化碳的产生联系起来(即热力学)。SPP“土壤系统”的主要目标是将基于能量的描述与生物相互作用相结合，以获得土壤周转过程的系统概念。在这一框架内，拟议的项目将评估土壤微生物群中的碳和能量流动，重点是营养网络。微食物网的结构和功能将以线虫为模型组进行分配。它们的代谢足迹是对营养水平较高的生产和放牧活动的基于特征的测量。线虫由于其高度的丰度以及物种和营养多样性，形成了微生物-动物群相互作用中的一个关键群体。该项目将解决三个主要问题：(1)不同功能组的食草动物及其相互作用(如资源竞争、行业内捕食)对细菌和真菌通道中的C和能量流动有什么影响？(2)土壤环境(即土壤类型、土壤有机质含量、底物、水分、温度)如何影响食草动物的多样性和活动，以及C通量到更高的营养水平？(3)微生物在动物肠道中对C从资源中分配的作用是什么，它们是否形成了一个“隐藏的”C通道？与合作项目一起，将进行PLFA、DNA和蛋白质-SIP(稳定同位素探测)以及元基因组学的组合，提供关于碎屑层关键微生物组成员的身份、继承和功能生态位划分的特殊详细程度。总体而言，拟议的项目将对微型食物网中的过程提供一个系统的观点，将碳周转(途径)和能量变化(热产生)与微生物组(活动、官能团、营养相互作用)联系起来。

Soil ecosystems are driven by carbon (C), nutrient and energy flows, which are essential for biogeochemical cycles. In particular, the organisms in the soil microbiome are channeling these fluxes. However, only few attempts were made to link microbial traits and functional groups of faunal grazers to heat and CO2 production (i.e. thermodynamics). The major goal of the SPP “SoilSystems” is to integrate energy-based descriptions with biotic interactions to gain a systemic concept for turnover processes in soil. Within this framework the proposed project will assess C and energy flux in the soil microbiome with the focus on trophic networks. The structure and function of the micro-food web will be assigned using nematodes as model group. Their metabolic footprints serve as trait based measurement for production and grazing activity of higher trophic levels. With their high abundance as well as species and trophic diversity nematodes form a key group in microbial-faunal interactions. Three major questions will be addressed by the project: (1) What is the impact of different functional groups of grazers as well as their interactions (e.g. resource competition, intraguild predation) on the C and energy flux in the bacterial and fungal channel? (2) How does the soil environment (i.e. soil type, soil organic matter content, substrate, moisture, temperature) affect grazer diversity and activity, and the C flux to higher trophic levels? (3) What role play microorganisms in the gut of faunal grazers for C allocation from resources and do they form a “hidden” C channel? Together with collaborating projects, a combination of PLFA-, DNA- and Protein-SIP (Stable Isotope Probing) as well as metagenomics will be performed, providing an exceptional level of detail on the identities, succession and functional niche partitioning of key microbiome members in the detritusphere. Overall, the proposed project will deliver a systemic view on the processes in the micro-food web, relating C turnover (pathways) and changes in energy (heat production) and to the microbiome (activity, functional groups, trophic interactions).