Anaya Garg

The origin of bacteria responsible for post-mortem bone decomposition remains debated, with researchers attributing it to either the enteric cavity of the decomposing organism or the exogenous soil microbiome. This distinction is critical, as bacterial colony presence and subsequent bacterial erosion patterns can provide key evidence for validating burial contexts in forensic investigations and archaeological site assessments. This evidence may provide strategies for the estimation of post-mortem interval as well as preservation methods for archeological skeletal remains. Bone degradation occurs through Gram-positive and Gram-negative bacteria producing collagenases that break down collagen, facilitating microbial colonization. Past studies primarily inferred bacterial origins by analyzing erosion traces post bacterial colonization, whereas recent work by the co-PI, Dr. Caroline Rowe, tracked bacterial translocation into bones, comparing articulated and disarticulated rat remains in different burial conditions. That study qualitatively assessed bacterial activity, while this research quantifies differences in bacterial translocation on periosteal and endosteal surfaces to establish statistical significance. Bacterial colonies were quantified using QuPath software, analyzing histological microscopy images to assess colonization, erosion extent, and surface modification. Findings indicate that bacterial origin significantly influences bone degradation. Enteric bacteria initiate more extensive erosion under certain conditions, whereas exogenous bacteria contribute to a distinct but less aggressive pattern. However, sustained decomposition requires a rich microbial soil environment. These results underscore the necessity of considering both enteric and environmental bacterial contributions in forensic and archaeological investigations, improving burial site verification and decomposition modeling.