Analysis of postmortem intestinal microbiota successional patterns with application in postmortem interval estimation

Abstract Microorganism plays a vital role in the decomposition of vertebrate remains in nature nutrient cycling, where the postmortem microbial succession patterns during decomposition remain unclear. Here, hierarchical clustering based on Manhattan distances analyzed the similarity and difference among postmortem intestine microbial succession patterns from microbial 16S rDNA sequences in a mouse decomposition model. Based on the similarity, seven different classes of succession patterns are obtained. Generally, the normal intestinal flora in the cecum gradually decreases with changes in living conditions after death, while some facultative anaerobes and obligate anaerobes grew and multiplied with oxygen consumption. Furthermore, a random forest regression model is developed to predict postmortem interval with the microbial succession trend data set. The model demonstrates a mean absolute error of 20.01 hours and a squared correlation coefficient of 0.95 during 15-day decomposition. Lactobacillus, Dubosiella, Enterococcus, and Lachnospiraceae NK4A136 group are considered as significant biomarkers for this model according to the ranked list. This study explores microbial succession patterns in terms of relative abundances and variety, aiding in predicting postmortem intervals, offering some knowledge of microbial behaviors in decomposition ecology.