DOM-microbe interactions shape carbon storage strategies in rhizosphere and detritus-rich wetland soils

Wetland macrophytes are associated with carbon storage through photosynthetic CO₂ uptake and interactions with microbes. Rhizodeposition and detritus accumulation represent two key pathways examined in this study. However, how dissolved organic matter (DOM) interacts with microbial carbon storage remains incompletely understood. Here, we investigated links between DOM characteristics and microbial carbon transformation pathways in Wuchang Lake using FT-ICR-MS, metagenomics, and geochemical analyses. Macrophyte presence was associated with a higher relative abundance of genes related to microbial carbon storage potential compared to macrophyte-free areas. Microbial taxa and carbon transformation strategies varied between rhizosphere and detritus-enriched soils and were associated with differences in DOM properties. In the rhizosphere, DOM with low H/C ratios (<1.5) and high number of transformations (>10) was associated with taxa linked to biomass degradation. In detritus-enriched soils, DOM with higher H/C ratios and lower carbon-to-phosphorus ratios (C:P) was associated with higher relative abundance of genes related to intracellular carbon storage, while genes associated with CO₂ and CH₄ production showed lower relative abundance. These communities also showed higher relative abundance of CO₂ fixation genes. Overall, DOM molecular characteristics were associated with niche-specific microbial carbon transformation patterns, providing a conceptual framework for wetland carbon dynamics.