Bacteria: The Grim Reaper’s Personal Stopwatch

When a person passes, depending on the lifestyle they lived, their fluttering souls are greeted by the weeping of the loving and the wailing of the grieving. Though their houses and homes are etched with a sorrowful emptiness that is inimical when noticed by the grieving. Regardless, their decaying bodies themselves provide a whole new world for bacteria, and with each passing period of time, a new era is born with different types of bacteria. This sequence at which bacteria colonize the body is different and hence is used universally across the world to measure the time of death called the Post-Mortem Interval (PMI) Estimation (Moitas et al.). It is questionable why people would need to measure such a thing but the answer lies in the malice hidden inside every human being. This interval is most useful in cases of murder and foul play where the time of death provides a lot of intel on the perpetrator.

To rot. An inevitable process of an organism decaying down to its most insoluble layers due to action of a bacteria, fungus or another natural process (“Merriam-Webster Dictionary”). 

As for the human body, the first stage holds the most nauseating effects. In the first 24 hours or so, oxygen is still present in tissues, which allows specific aerobic bacteria such as Staphylococcus and Corynebacterium to reproduce quicker then it would in the average open wound (these are the ones that cause skin infections) (Hyde et al.). The bacteria located in the gut start to digest the intestinal walls and tear their way out and hence the invasion begins. 

Within the first week, the metabolic processes of gut bacteria such as Clostridium (helps break down carbs) cause the build up of gases such as methane and sulfides which causes the process of putrefaction or more repulsively, bloating (Gill-King, 1997). Pretty similar to how whales explode after they die intact. The main signs apart from this bloating process includes the leaking of bodily fluids and the colour change of the skin to greenish-black (Vass, 2001).

Active decay starts between the first week and a full month, which is when the bloating starts to rupture, increasing the release of nutrient rich fluids which attract not only more bacteria but other multicellular organisms as well. Proteolytic bacteria such as Clostridium start to break down soft tissues and fats. Flies and maggots, attracted by the stench, make great contributions in spreading the bacteria (Weiler). Try picturing that in your head. Or not.

As multiple weeks past, the decomposition starts to drop from its peak as most soft tissue is consumed. Most bacteria would begin dying out here but soil bacteria along with fungi will start to dominate the domain. These break down what's left of organic material until nothing remains except the usual metabolic waste material. Luckily and unluckily at the same time, most bodies are found before they are completely wiped out of existence as bones, hair and nails tend to liquify harder than flesh (Staughton).

After all that, simple cotton swabs are all that is needed to calculate the PMI estimates as these are used to identify the stage of the decomposition process. Samples are taken from the gut, skin and surrounding area and are compared with preknown decomposition timeline in order to refine the PMI estimates (Johnson et al.).

“From my rotting body, flowers shall grow and I am in them, and that is eternity.”

~ Edvard Munch

Bibliography

Moitas, Bruna, et al. “Microbiology and Postmortem Interval: A Systematic Review.” Forensic Science Medicine and Pathology, vol. 20, no. 2, Springer Science+Business Media, Oct. 2023, pp. 696–715, https://doi.org/10.1007/s12024-023-00733-z. Accessed 13 Feb. 2025.

“Merriam-Webster Dictionary.” Merriam-Webster.com, 13 Feb. 2025, www.merriam-webster.com/dictionary/rot? Accessed 13 Feb. 2025.

Hyde, Embriette R., et al. “Initial Insights into Bacterial Succession during Human Decomposition.” International Journal of Legal Medicine, vol. 129, no. 3, Springer Science+Business Media, Nov. 2014, pp. 661–71, https://doi.org/10.1007/s00414-014-1128-4. Accessed 18 Feb. 2025.

‌Gill-King, H. (1997). "Chemical and Ultrastructural Aspects of Decomposition." In Forensic Taphonomy: The Postmortem Fate of Human Remains (pp. 93-108). CRC Press.

‌ Vass, A. A. (2001). "Beyond the Grave—Understanding Human Decomposition." Microbiology Today, 28(4), 190-192.

Julia Weiler. “When Maggots Solve a Murder.” Newsportal - Ruhr-Universität Bochum, 29 Mar. 2022, news.rub.de/english/2022-03-29-biology-when-maggots-solve-murder. Accessed 19 Feb. 2025.

Staughton, John. “ScienceABC.” ScienceABC, 21 Dec. 2015, www.scienceabc.com/humans/skeleton-mystery-dont-bones-decay-decompose.htmlAccessed 19 Feb. 2025.

‌Johnson, Hunter R., et al. “A Machine Learning Approach for Using the Postmortem Skin Microbiome to Estimate the Postmortem Interval.” PLoS ONE, vol. 11, no. 12, Public Library of Science, Dec. 2016, pp. e0167370–70, https://doi.org/10.1371/journal.pone.0167370. Accessed 19 Feb. 2025