Microbial breakdown of organic material is one of the most important processes on earth, yet enormous knowledge gaps exist about its controls. We demonstrate that a universal, inter-kingdom microbial network assembles in response to nutrient-rich, terrestrial mammalian decomposition, despite selection effects of location, climate and season. We created the first metagenome-assembled genome library from mammalian decomposition-associated soils and combined it with metabolomics to identify a microbial decomposer network that interacts by cross-feeding to efficiently metabolize labile decomposition products. The key fungal and bacterial decomposers appear unique to the breakdown of terrestrial cadavers, and are rare in relative abundance across non-decomposition environments. Blow flies are suggested as an important decomposer vector and the observed lockstep of microbial interactions underlies a robust microbial forensic tool for predicting the time since death.
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