This study combined deep microbial community characterization, community-level metabolic reconstruction, and soil biogeochemical assessment to understand principles governing microbial community assembly during decomposition of mouse and human corpses on different soil substrates.
The death of a large animal represents a food bonanza for microorganisms. The authors monitored microbial activity during the decomposition of mouse and human cadavers. Regardless of soil type, season, or species, the microbial succession during decomposition was a predictable measure of time since death. An overlying corpse leaches nutrients that allow soil- and insect-associated fungi and bacteria to grow. These microorganisms are metabolic specialists that convert proteins and lipids into foul-smelling compounds such as cadaverine, putrescine, and ammonia, whose signature may persist in the soil long after a corpse has been removed. Vertebrate corpse decomposition provides an important stage in nutrient cycling in most terrestrial habitats, yet microbially mediated processes are poorly understood. The current study identified a suite of bacterial and fungal groups contributing to nitrogen cycling and a reproducible network of decomposers that emerge on predictable timescales. The results show this decomposer community is derived primarily from bulk soil, but key decomposers are ubiquitous in low abundance. Soil type was not a dominant factor driving community development and the process of decomposition is sufficiently reproducible that it offers unique opportunities for forensic investigations. (Publisher abstract modified)