Forensically significant microbial community responses to aboveground cadaver decomposition in Southeast Texas soils

Abstract

During vertebrate decomposition, a purge of nutrient‐rich fluids enters the surrounding soil producing a localized nutrient hotspot. The composition of microbial communities at the soil surface is known to predictably change in response to this influx of decomposition fluids over time. However, the depth to which these compositional changes permeate the soil near a decomposing human cadaver and whether specific microbial members exhibit spatial responses to aboveground decomposition both represent significant knowledge gaps. In this study, we longitudinally sampled forest soils adjacent to decomposing human cadavers and from nearby control sites in 2 cm increments to a depth of 10 cm. Soil samples were collected during purge, post purge, and the dry remains stage of decomposition over three seasons at Sam Houston State University's Southeast Texas Applied Forensic Science facility. We detected season‐dependent microbial community responses in the upper 0–4 cm of soils adjacent to decomposition fluids. On average, microbial community diversity decreased and community composition became increasingly different in comparison to nearby control soils. Cadaver soils remained impacted for the duration of the 4.5‐month spring trial and 1.5‐month summer trial. Terriglobus , Acidisoma , Ignatzschineria , and Pandoraea may represent forensically informative biological markers, as they significantly increased in response to decomposition. We observed a more limited, yet still detectable response in the lower 6–10 cm of soil. In addition to improving our understanding of decomposition ecology, we anticipate that incorporating these findings into forensic investigations could help strengthen postmortem interval model estimation and better inform investigative sampling practices.