How bacteria change as a corpse decays

Posted Nov 14, 2013 by Tim Sandle
The composition of bacteria changes as body decays. Some researchers have started to call this altering community the "necrobiome." By studying this community researchers are beginning to piece together the "ecology of death."
A Petri dish map of artist Sonja Bäumel s body shape.
A Petri dish map of artist Sonja Bäumel's body shape.
Sonja Bäumel
A scientific study reported as few weeks ago, showing how the microbial community living on dead mice changed in a consistent pattern, suggested that this could help establish time of death. The Digital Journal reported that this could one day help establish the time that the crime of murder took place.
Some new research sheds further light on the alterations to the microbial composition of a body as it decomposes. With this study, researchers in Texas studied two human cadavers during one important stage of decomposition: bloat. With bloat, as the body decays, bacteria growing inside the body produce gases such as hydrogen sulfide and methane. These gases inflate the cadaver and eventually force fluids out in a purge, or rupture event.
The timing of bloat can vary somewhat, however it is a recognizable stage of decomposition in medical pathology.
For the study, two people donated their bodies to medical science. The bodies, Science News notes, were allowed to decompose under "natural" outdoor conditions at the Southeast Texas Applied Forensic Science facility. The research team took samples from sampled the mouth and rectum, since these area have high microbial populations.
The sampled bacteria were then subjected to genetic testing. During the bloat period, the dominant bacteria were anaerobic bacteria such as Clostridia (indicating oxygen-free areas). From this starting point, the research team hope to build up a library of yield forensically useful information such as time of death.
The new research has been published in the journal PLOS One, in a paper titled “The Living Dead: Bacterial Community Structure of a Cadaver at the Onset and End of the Bloat Stage of Decomposition.”