THE EFFECTS OF MICROBIAL ACTIVITY ON BONE MICROSTRUCTURE AND COLLAGEN

The biological processes that occur after an animal’s death and their effects on bone preservation are still poorly understood. Bone is generally the predominant material that is preserved from vertebrates, but during fossilization this material experiences diagenesis which can accelerate the decomposition of collagen, a key component of bone structure, by bacteria and fungi. The goal of this study is to improve our understanding of post-mortem diagenesis and the role bioerosion plays in accelerating collagen deterioration, a crucial factor in the preservation of bone in the archaeological and paleontological record. Previous collagenase assays and bone structural analyses with Fourier transform infrared spectroscopy on three recently decomposed North American beavers revealed that certain bones exhibited active collagen breakdown. However, there was no correlation between active collagen breakdown with bone structure. Increased collagenase activity in post-mortem bones has often been connected to microbial attack, which can leave behind distinct morphological “traces” in bone based on the causative agents. Using previous collagenase assay results, bones were selected based on active and non-active collagenase activity and will undergo a petrographic analysis to determine if there is a correlation between collagen breakdown and microbial attack on bone microstructure. Bones that have experienced active collagen breakdown are hypothesized to have greater rates of microbial attack. The most destruction is expected to occur in the vertebrae and ribs due to their proximity to the gastrointestinal tract as well as displaying active collagen breakdown in two of the three specimens. Point counting will also be conducted to estimate proportions of boring types for each bone thin section to assign likely causative microorganism(s). Fungal borings are expected to be the primary bioerosion type based on prior research that found animal bones experience more bioerosion from fungi than bacteria. Studying modern post-mortem processes not only expands our understanding of fossilization, but also forensic science. Diagenetic processes can alter the preservation of key identifying markers (i.e., DNA) and understanding this alteration may provide important information for forensic science.