Mineralization, stabilization, and re-mobilization of organic substances in microhabitats - the role of microorganisms in carbon and energy flows (MicroHabits)

土壤微生物对碳矿化和稳定的重要性越来越被认识到，并通过微生物碳泵的概念进行了描述。然而，迄今为止，这个框架内的潜在机制和控制尚不清楚，过去的大多数研究只关注C动态的特定方面。为了填补这一空白，我们计划将微生物碳泵的概念与三个重要的微栖息地联系起来，以了解碳矿化（碎屑层）、碳稳定（矿物表面）和碳再动员（蚯蚓铸件）阶段的碳流。当前提案的新挑战是通过将C和微生物动力学与能量通量和热力学原理联系起来，提高我们的概念理解。我们将在一系列微观实验中解决这一挑战，在这些实验中，我们将结合同位素（全质量平衡，包括13Cmic， 13C PLFA，13C氨基糖，13Corg,13C- eoc）以及量热（产热）和分子生物学（qPCR， Illumina PCR扩增子测序，DNA-SIP）方法，跟踪纤维素和玉米凋落物中的13C和能量流。对线虫的分析将证明C和能量流向更高的营养水平。我们的建议的一部分是三个互补的核心实验之一，它们共同覆盖了SPP中提出的土壤，基质和边界条件的整个潜在数据空间，这些核心实验获得的数据将提供给整个SPP。总之，我们的项目将强调特定微栖息地对土壤中微生物稳定C的重要性。

The importance of soil microorganisms for carbon mineralization and stabilization is increasingly recognized and described through the concept of the microbial C pump. However, the underlying mechanisms and controls within this framework are to date poorly understood and most studies in the past have focused only on specific aspects of C dynamics. We plan to fill this gap by linking the concept of the microbial C pump to three important microhabitats to understand the carbon flow during phases of C mineralization (detritusphere), C stabilization (mineral surfaces), and C re-mobilization (earthworm casts). The new challenge for the current proposal is to improve our conceptual understanding by linking C and microbial dynamics to energy fluxes and thermodynamic principles. We will address this challenge in a series of microcosm experiments in which we will follow 13C and energy flow from cellulose and maize litter into different pools combining isotopic (full mass balances including 13Cmic, 13C PLFA,13C amino-sugars,13Corg,13C-EOC) with calorimetric (heat production) and molecular biological (qPCR, Illumina PCR amplicon sequencing, DNA-SIP) methods. Analyses of nematodes will demonstrate C and energy flow into higher trophic levels. One part of our proposal is one of three complementary core experiments, which together cover the entire potential data space of soils, substrates, and boundary conditions proposed in the SPP. The data obtained in these core experiments will be available to the whole SPP. In conclusion, our project will underline the importance of specific microhabitats for the microbial role of C stabilization in soil.