Clay-organic matter interactions drive microbial necromass preservation in soils

作者：Xu Wang, Cynthia M. Kallenbach, Maya Almaraz, Katerina Georgiou, Lifei Sun, Changpeng Sang, Ping Jiang, Yue Liu, Edith Bai, Chao Wang · 发表于：Nature Communications · 年份：2026 · DOI：10.1038/s41467-026-70156-1 · 被引用次数：3 · 研究领域：Soil Carbon and Nitrogen Dynamics、Clay minerals and soil interactions、Microbial Community Ecology and Physiology

Microbial necromass is increasingly recognized as a major source of stable soil organic matter (SOM), and its persistence is often attributed to interactions with clay-sized minerals. However, the mechanisms underlying this mineral-mediated stabilization remain poorly understood. Here, we conducted an in situ dual-labeled (13C and 15N) microbial necromass experiment across a clay gradient to quantify how clay content and necromass origin (bacterial vs. fungal) regulate necromass persistence. We find that higher clay content markedly enhances necromass retention by strengthening mineral protection, suppressing microbial activity and diversity, and limiting leaching losses. NanoSIMS imaging shows that new necromass preferentially associates with organic matter coatings on the rough mineral surfaces, highlighting organo-organic interfaces as important stabilization pathways. Necromass origin exerts little effect on retention despite marked differences in C:N ratios and bulk chemical composition, indicating that finer-scale molecular features, rather than broad compositional differences, govern necromass stabilization in soils. By incubating isotope-labeled microbial necromass in the field, the study shows that new microbial necromass preferentially associate with organic matter coatings on rough mineral surfaces rather than adhering to bare minerals.