The forensic microbiome: investigation of the microbiome for time since death estimation and human identification

Diverse communities of microorganisms exist on and within the human body, as well as in other environments such as soil. The total genetic material contributed by microbes to a specific environment is known as the microbiome. Cell cultures has been used in the identification of bacteria and fungi, but the limitations of cultures mean that not all species of bacteria/fungi from a sample can be cultured successfully, particularly strict anaerobic bacteria, which would die in the presence of oxygen. Due to advances in next generation sequencing (NGS) techniques, metabarcoding – which allows the identification of various microorganisms within a sample from an environment using a short section of DNA from a specific gene – is now possible. This means that changes or differences in microbiome of environmental or human samples can now be characterized. The differences in the microbiome observed among individuals has been shown to occur due to factors such as diet, lifestyle, and health status of its host. Also, the microbiome of grave soil changes in a successive and reproducible manner, as various microorganisms thrive in the conditions that accompany the various stages of decomposition of a body. This, therefore, presents the potential of the microbiome to be used in human identification and time since death estimation.