Forensic microbiology has gained recognition in recent years for its utility in postmortem interval (PMI) estimation. I conducted my research at the NMU Forensic Research Outdoor Station (FROST), one of 10 facilities in North America dedicated to research involving human taphonomy (the study of all factors that affect the body after death). The main purpose of this research is to explore relationships between the necrobiome (bacteria and other microbes associated with human remains) and the soil microbiome. Two guiding research questions are: 1. Is the human necrobiome detectable in soil surrounding a decomposing body? and 2. Does the concentration of the human necrobiome in the soil change with time and distance? To answer these questions, soil samples were systematically collected on three separate dates from an area surrounding a human donor at FROST. Samples were collected from the surface and from 10cm below the surface using a soil probe. Control samples were also collected and analyzed for comparative purposes. Bacterial DNA was extracted and isolated from each soil sample using the DNeasy Powersoil Kit from Qiagen. After bacterial 16S sequencing of the

samples at Michigan State University, bioinformatics analysis sorted the DNA sequences into the appropriate bacterial classifications (phyla, classes, orders, families, and genuses). Results show which bacteria are present and in what relative concentrations. These concentrations and the spatial and temporal analyses could have applications in medicolegal death investigations and PMI estimation. Knowing how long a body has been in a location may help investigators identify victims and/or possible suspects.

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Dr. Josh Sharp

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