Discipline: Biological Sciences
Subcategory: STEM Research
- Alabama State University
Co-Author(s): Jessica Carter and Sheree Finley, Alabama State University, Montgomery, AL
A first-of-its-kind study on an emerging topic of the human thanatomicrobiome (thanatos-, Greek for death) has pinpointed Clostridium spp. as the specific bacteria that are the primary mediators of putrefaction in internal organs. This groundbreaking research also introduces and describes a new scientific concept, the Postmortem Clostridium Effect (PCE), which elucidates some of the roles that Clostridium spp. play during human putrefaction. The study encompasses one of the largest cohort of cadavers to date and adds empirical data to the Human Postmortem Microbiome Project (HPMP). Although Clostridium is ubiquitous in internal organs of decaying corpses, there are large gaps in our knowledge of the role that the bacteria contributes. The findings of our previous thanatomicrobiome studies discovered that a majority of microorganisms in the human body after death are the obligate anaerobes, Clostridia. Furthermore, we found that Clostridium spp. predominate at long times since death (up to 10 days). The current study compared the microbial communities profiled by amplicon-based sequencing of the 16S rRNA gene V4 and V3-4 hypervariable regions. We investigated spleen and liver tissues of 45 cadavers and determined that Clostridium spp. also predominate at shorter times since death (4 hours). We attribute Clostridium’s high abundance in decomposing human bodies to three factors. First, Clostridium has a very fast growth rate. C. perfringens has the most rapid doubling time of approximately 7.4 minutes at optimal temperatures. Next, the bacteria have effective proteolytic functions. Clostridium spp. have collagenases that digest vertebrate collagen that permit access to gut epithelia and allow transmigration to other tissues such as liver and spleen. Lastly, Clostridium spp.’s anaerobic nature lends to effective decomposition. Decaying corpses’ internal organs lack oxygen which facilitates the rapid growth of anaerobic bacteria in nutrient-rich hosts. A future research question would be, “What kind of abiotic and biotic factors does the Postmortem Clostridium Effect have on microbial communities in human cadavers from different geographical locations?”
Funder Acknowledgement(s): National Science Foundation HRD 1401075
Faculty Advisor: None Listed,