The authors of this paper report on their development of a statistical model that explained most of the time since placement of vertebrate remains in a field, documenting and identifying differences in bacterial communities to expand knowledge of the carrion microbiome, and discussing its applicability to forensic science; they also present a new framework and standard operating procedure that uses high throughput metagenomic sequencing.
Decomposition studies of vertebrate remains primarily focus on data that can be seen with the naked eye, such as arthropod or vertebrate scavenger activity, with little regard for what might be occurring with the microorganism community. Here, the authors discuss the necrobiome, or community of organisms associated with the decomposition of remains, specifically, the “epinecrotic” bacterial community succession throughout decomposition of vertebrate carrion. Pyrosequencing was used to (1) detect and identify bacterial community abundance patterns that described discrete time points of the decomposition process and (2) identify bacterial taxa important for estimating physiological time, a time–temperature metric that is often commensurate with minimum post-mortem interval estimates, via thermal summation models. There were significant bacterial community structure differences in taxon richness and relative abundance patterns through the decomposition process at both phylum and family taxonomic classification levels. The authors found a significant negative linear relationship for overall phylum and family taxon richness as decomposition progressed. Additionally, they developed a statistical model using high throughput sequencing data of epinecrotic bacterial communities on vertebrate remains that explained 94.4 percent of the time since placement of remains in the field, which was within two-to-three hours of death. These bacteria taxa are potentially useful for estimating the minimum post-mortem interval. Lastly, the authors provide a new framework and standard operating procedure of how this novel approach of using high throughput metagenomic sequencing has remarkable potential as a new forensic tool. Documenting and identifying differences in bacterial communities is key to advancing knowledge of the carrion necrobiome and its applicability in forensic science. (Published Abstract Provided)