Qi Shanshan, Wang Gangsheng, Li Wanyu, Zhou Shuhao
State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan, 430072, China.
Institute for Water-Carbon Cycles and Carbon Neutrality, School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan, 430072, China.
ISME Commun. 2023 Nov 20;3(1):121. doi: 10.1038/s43705-023-00331-8.
Enzyme allocation (or synthesis) is a crucial microbial trait that mediates soil biogeochemical cycles and their responses to climate change. However, few microbial ecological models address this trait, particularly concerning multiple enzyme functional groups that regulate complex biogeochemical processes. Here, we aim to fill this gap by developing a COmpetitive Dynamic Enzyme ALlocation (CODEAL) scheme for six enzyme groups that act as indicators of inorganic nitrogen (N) transformations in the Microbial-ENzyme Decomposition (MEND) model. This allocation scheme employs time-variant allocation coefficients for each enzyme group, fostering mutual competition among the multiple groups. We show that the principle of enzyme cost minimization is achieved by using the substrate's saturation level as the factor for enzyme allocation, resulting in an enzyme-efficient pathway with minimal enzyme cost per unit metabolic flux. It suggests that the relative substrate availability affects the trade-off between enzyme production and metabolic flux. Our research has the potential to give insights into the nuanced dynamics of the N cycle and inspire the evolving landscape of enzyme-mediated biogeochemical processes in microbial ecological modeling, which is gaining increasing attention.
酶分配（或合成）是一种关键的微生物特性，它介导土壤生物地球化学循环及其对气候变化的响应。然而，很少有微生物生态模型涉及这一特性，特别是关于调节复杂生物地球化学过程的多种酶功能组。在此，我们旨在通过为六个酶组开发一种竞争性动态酶分配（CODEAL）方案来填补这一空白，这六个酶组在微生物酶分解（MEND）模型中作为无机氮（N）转化的指标。该分配方案为每个酶组采用随时间变化的分配系数，促进多个组之间的相互竞争。我们表明，通过使用底物的饱和水平作为酶分配的因素，实现了酶成本最小化原则，从而形成了一种酶效率高的途径，每单位代谢通量的酶成本最低。这表明相对底物可用性影响酶产生和代谢通量之间的权衡。我们的研究有可能深入了解氮循环的细微动态，并激发微生物生态建模中酶介导的生物地球化学过程不断演变的格局，这一领域正受到越来越多的关注。
