The thanatomicrobiome: a new direction in forensic science to determine the post-mortem interval

Identifier:  TFM:561

Handle: https://hdl.handle.net/20.500.11797/TFM561

Authors:  Clavero Mateu, Núria

Abstract:
For hundreds of years, it has been well known that microbes play an essential role in the decomposition of corpses, but it was not until recent years that researchers gave them the importance they deserved. The body of a healthy person is made up of organs inhabited by microbes such as the gastrointestinal tract and sterile organs, however, once death has occurred, they are all colonized both by microbes from the gastrointestinal tract and microbes from the environment. The migration from the gastrointestinal tract to the rest of the internal organs follows a specific order and starts earlier at organs closer to the gastrointestinal tract and finishes at more distant organs. Moreover, the microbial communities change with time due that at different stages of the decomposition oxygen availability differs. All these microbes and especially bacteria constitute the thanatomicrobiome and have the potential to determinate the post-mortem interval. To study the succession of the thanatomicrobiome most researches use animal models but only a few of them human corpses from criminal cases or donations. Microbial communities are mostly analysed with 16S rRNA a genetic marker for bacteria and archaea and metagenomic whole-genome shotgun sequencing. Results are interpreted using alpha and beta diversity metric values and compared to databases. Results from multiple investigations demonstrate that the most prominent phyla are Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria which coincide with the GIT microbiome and that with time Proteobacteria declines and Firmicutes becomes the most abundant phylum. Furthermore, multiple members of the phylum Firmicutes such as some species of Clostridium and Lactobacillus exhibit time signals. Nevertheless, although the results seem promising the thanatomicrobiome is highly influenced by extrinsic and intrinsic factors and therefore cannot be used as a model to predict the post-mortem interval in the present but probably will be crucial in future forensic investigations.