Frozen: Thawing and Its Effect on the Postmortem Microbiome in Two Pediatric Cases

Previous postmortem microbiome studies have focused on characterizing taxa turnover during an undisturbed decomposition process. How coexisting conditions (e.g., frozen, buried, burned) affect the human microbiome at the time of discovery is less well understood. Microbiome data were collected from two pediatric cases at the Wayne County Medical Examiner in Michigan. The bodies were found frozen, hidden in a freezer for an extended time. Microbial communities were sampled from six external anatomic locations at three time points during the thawing process, prior to autopsy. The 16S rRNA V4 gene amplicon region was sequenced using high-throughput sequencing (Illumina MiSeq). Microbial diversity increased, and there was a distinct shift in microbial community structure and abundance throughout the thawing process. Overall, these data demonstrate that the postmortem human microbiome changes during the thawing process, and have important forensic implications when bodies have been substantially altered, modified, and concealed after death.