作者：Huang, Z., Liu, H., Wang, C., Wang, J., Tian, C., Feng, J., Shen, J. & Wang, X.

Plateau lakes are highly sensitive to climate change and anthropogenic disturbances. The intensification of seasonal variations caused by global warming has complicated the biogeochemical interactions between dissolved organic matter (DOM) and microbial communities. However, how DOM's chemical composition regulates microbial community dynamics and carbon cycling under varying trophic states and seasonal conditions remains unclear. Here, we employed Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and metagenomic sequencing to investigate the seasonal and trophic controls on DOM composition, microbial communities, and carbon cycling in plateau lakes. The results showed that in the dry season, DOM in the eutrophic lake exhibited pronounced aromaticity, with carboxyl-rich alicyclic molecules (CRAMs) constituting 42.80 % of the molecular pool. Conversely, during the wet season, sulfur-and nitrogen-containing compounds like CHOS and CHONS significantly increased, particularly in the eutrophic lake. The oligotrophic lake displayed the highest molecular lability, characterized by hydrogen-to-carbon (H/C) ratios of 1.24 and molecular lability indices (MLB%) of 34.76 %. Eutrophication altered microbial interaction networks, enhancing interspecies interactions and metabolic specialization. This metabolic shift drove preferential utilization of labile sugars in dry seasons and facilitated the degradation of recalcitrant carbon substrates in wet seasons, thereby optimizing carbon source partitioning. Notably, mesotrophic and oligotrophic lakes fostered resource cooperation by reducing network modularity and shaping carbon cycling through the coordinated action of multiple microbial groups. This study elucidates that carbon cycling in plateau lakes is governed by synergistic effects of trophic states and seasonal dynamics, with DOM serving as a critical mediator in microbial-driven carbon cycling dynamics.

高原湖泊对气候变化和人为干扰极为敏感。全球变暖导致的季节性变化加剧，使溶解性有机质（DOM）与微生物群落之间的生物地球化学相互作用变得复杂。然而，在不同营养状态和季节条件下，DOM 的化学组成如何调控微生物群落动态和碳循环仍不明确。本研究采用傅里叶变换离子回旋共振质谱（FT-ICR MS）和宏基因组测序技术，探究了高原湖泊中 DOM 组成、微生物群落及碳循环的季节性和营养调控机制。结果显示，旱季富营养化湖泊中的 DOM 具有显著的芳香性，其中富含羧基的脂环族分子（CRAMs）占分子库的 42.80%。相反，雨季时，含硫和含氮化合物（如 CHOS 和 CHONS）显著增加，尤其是在富营养化湖泊中。贫营养化湖泊的分子易降解性最高，氢碳比（H/C）为 1.24，分子易降解指数（MLB%）为 34.76%。富营养化改变了微生物相互作用网络，增强了种间相互作用和代谢特化。这种代谢转变促使微生物在旱季优先利用易降解糖类，并在雨季促进难降解碳基质的降解，从而优化碳源分配。值得注意的是，中营养和贫营养湖泊通过降低网络模块性促进资源合作，并通过多个微生物类群的协同作用影响碳循环。本研究阐明，高原湖泊的碳循环受营养状态和季节动态的协同作用调控，而 DOM 在微生物驱动的碳循环动态中充当关键媒介。

（来源：Water Research  2026   DOI: 10.1016/j.watres.2025.125312）