Discipline: Biological Sciences
Brittany Hume-Dawson - Alabama State University
Co-Author(s): Courtnee Bell, Alabama State University, Montgomery, AL; Sheree Finley, Alabama State University, Montgomery, AL; Gulnaz Javan, Alabama State University, Montgomery, AL.
Escherichia coli is a normal resident of the human intestinal microbiota; however, recent studies have demonstrated the existence of this microbe in postmortem brain tissues. E. coli has been shown to successfully translocate from blood to the central nervous system in both in vitro and in vivo blood brain barrier models. Studies from the Thanatos Lab at Alabama State University have revealed distinct thanatomicrobiota (microbiota of death) signatures in human body sites after death. Thanatomicrobiome studies attest that postmortem microbial succession may have the potential to reveal essential microbiota biomarkers for the identification of time of death. As microbial cells increase and human cells decline, the corresponding numbers depend on many abiotic and biotic environmental factors. Therefore, determining the diversity of microbial communities located in internal body sites, using bioinformatics and machine-learning tools, has the potential to be a useful biomarker in forensic microbiology. The brain is identified as an intermediate-decomposing body site in the progression of the natural order of human decomposition. In this study, we performed 16S rRNA amplicon-based sequencing on the brain tissues from 22 cadavers. Postmortem samples were collected from cases with times of death ranging from short (8 hours) to long (11 days) from two different geographic locations i) Pensacola, FL and ii) Tampere, Finland. We hypothesize that as the human brain decomposes, microbial proliferation and diversity will increase with time of death. The relative abundances and the influence of individual case characteristics on microbiome indices such as species-richness and evenness were determined, and an analysis of covariance was performed. Escherichia were the predominant microbes in Finnish brain samples with greater than 50% of the relative abundance of the observed bacteria assigned to this genus. Conversely, Staphylococcus, Lactobacillus, and Streptococcus predominated brain samples from United States corpses. To date, these results represent the first study of its kind to connect gut-associated microbes to decomposing brain samples from actual criminal case cadavers using next-generation sequencing. A future research question would be: How did the bacteria get into the brain? Are specific types of bacterial species associated with specific organs? Here, this research encompasses the largest postmortem catalogue with the goal of identifying and characterizing thanatomicrobiota associated with decomposing vertebrates.
Funder Acknowledgement(s): National Institute of Justice 2017-MU-MU-0042 US National Science Foundation HBCU-UP HRD 1911660
Faculty Advisor: Dr. Gulnaz Javan, firstname.lastname@example.org
Role: In conducting this research I performed i) Phenol-Chlorofom DNA extraction, ii) Polymerase Chain Reaction, iii) E-Gel Electrophoresis System.