Soil Microbial Community Succession During Cadaver Decomposition

Microbes play critical roles in nutrient cycling in terrestrial ecosystems. In particular, microbial decomposition of organic matter is a key step in carbon and nutrient cycling, linking above-ground and below-ground pools. It is well known that the microbial community changes in structure and function following the introduction of organic matter into a terrestrial system. The decomposition of plant litter has been extensively investigated but the decomposition of animal-derived organic matter has often been overlooked. The unique characteristics of animal input are hypothesized to dictate a distinct decomposition process. This study examined the microbial community responsible for decomposition of animal-derived organic matter. Our objective was to determine the taxonomic and functional succession of microbial populations in a Cadaver Decomposition Island (CDI) during decomposition. To address our objectives, soils from beneath four cadavers at the UT Anthropological Facility were sampled throughout the decomposition process. Reproducible patterns in the concentration of extractable total nitrogen, ammonia and organic carbon in the soil were observed. The distinct trends in microbial respiration and net N mineralization rates indicated that a major functional shift in the community occurred following the Active Decay stage. Human-associated Bacteroides were detected at high concentrations throughout decomposition, up to 198 days after cadavers were first placed. This study revealed the succession in microbial community function and structure during decomposition of animal-derived organic matter, and has implications in the fields of public health and forensic science.