Substrate affects microbial driven distribution of energy and matter among organic carbon functional pools in soil - Driver Pool

微生物转化有机质是有机质长期储存的必要条件。因此，微生物通过酶活性代谢OM，将其转化为自身的生物质或呼吸以消耗能量。这导致能量和物质的流动，而这种流动被物质和剩余能量的不断循环所调节和延缓。转化的碳利用效率（CUE）取决于各种底物的性质（提供能量的质量）、微生物代谢、微生物组内的连通性和环境因素。为了模拟这种复杂的物质和能量的联合周转，需要一个更广义的概念。这需要一种基于热力学的方法来描述土壤中不同功能池之间的有机碳周转和分布水平上的转化和相互作用。此外，必须考虑过程动力学（速率），因为效率和速率之间的最佳权衡标志着过程的最佳。因此，项目驱动池的总体目标是了解能量通量/热力学平衡和基质周转途径之间的相互作用，这是由微生物丰度、群落结构和功能的变化所调节的。哪些是指导土壤有机质功能库中有机碳转化过程和分布的最相关的热力学驱动力？我们假设OM的周转是由能量通量控制的三种过程类型之间的相互作用驱动的，这三种过程类型在速率、能量平衡和消散、保持或积累吉布斯能量的趋势方面有所不同。此外，来自基质的有机碳可能分布在土壤中的各种功能池中，这些功能池可以在能量上区分为代表有序结构的“焓库”，如生物量和“（临时）熵库”，如超分子OM和坏死团块。该项目是一组协调的核心项目的一部分。计划在三个pi之间协调进行联合微观宇宙孵育实验。将在分配给三个pi的四个工作包中进行五个实验，测试添加到土壤中的七种基质的周转情况，其中大多数具有明确定义的分子和热力学性质。我们的目标是确定(i)微生物周转的能量和物质的完全平衡，（ii）微生物驱动过程的动力学，（iii）土壤功能池中基质分布的数量，以便（iv）找出哪些基质特性直接将能量和物质流入哪些池，分别导致基质特定的CUE， EUE和热流。最后，(v)结合WP 1-3的综合数据，建立一个基于平衡的热动力学模型。该模型将基于代表物质和能量通量之间联系的赫斯定律（用焓、熵、吉布斯能表示）。

Microbial transformation of organic matter (OM) is a necessity for long-term storage of SOM. Thereby, microorganisms metabolize OM through enzymatic activity, converting it into own biomass or respiring it for energy consumption. This results in a flux of energy and matter that is modulated and retarded by continuous recycling of matter and residual energy. The carbon use efficiency (CUE) of transformation depends on the properties of the various substrates (quality of provided energy), on the microbial metabolism, the connectivity within the microbiome, and environmental factors. In order to model that complex, combined turnover of matter and energy a more generalized conception is required. This asks for a thermodynamic-based approach describing transformations and interactions on the level of OC turnover and distribution among different functional pools in soil. Additionally, process kinetics (rates) must be considered because the optimum trade-off between efficiency and rate marks the process optimum.Hence, the overall aim of the project Driver Pool is to understand the interplay between energy fluxes/thermodynamic balances and substrate turnover pathways, modulated by shifts in microbial abundance, community structure and functioning. Which are the most relevant thermodynamic driving forces directing OC transformation processes and distribution among OM functional pools in soil? We hypothesize that OM turnover is driven by an energy flux-controlled interplay between three process types varying in their rate, energy balance and tendency to dissipate, keep or accumulate Gibbs energy. Furthermore, OC from substrates may be distributed among various functional pools in soil that can be energetically distinguished in “enthalpy storage pools” representing ordered structures like biomass and “(temporary) entropy storage pools” like supramolecular OM and necromass.The project is part of a group of coordinated core-projects. Joint microcosm incubation experiments were planned that are coordinated between the three PIs. The turnover of seven substrates, mostly with well-defined molecular and thermodynamic properties, added to soil will be tested in five experiments going across four work packages that are assigned to the three PIs. We aim to determine (i) complete balances of energy and matter for microbial turnover, (ii) kinetics of microbial driven processes and (iii) quantities of the distribution of substrates among soil functional pools, in order (iv) to find out which substrate properties direct fluxes of energy and matter into which pools, resulting in substrate specific CUE, EUE, and heat flow respectively. Finally, (v) a balance-based thermokinetic model will be developed integrating the combined data of WP 1-3. This model will be based on the law of Hess representing the connection between material and energy fluxes (formulated for enthalpy, entropy, Gibbs energy).