Microbial communities in the liver and brain are informative for postmortem submersion interval estimation in the late phase of decomposition: A study in mouse cadavers recovered from freshwater

Linlin Wang; Fuyuan Zhang; Kuo Zeng; Wenwen Dong; Huiya Yuan; Ziwei Wang; Jin Liu; Jiaqing Pan; Rui Zhao; Dawei Guan

doi:10.3389/fmicb.2022.1052808

Microbial communities in the liver and brain are informative for postmortem submersion interval estimation in the late phase of decomposition: A study in mouse cadavers recovered from freshwater

Front Microbiol. 2022 Nov 15:13:1052808. doi: 10.3389/fmicb.2022.1052808. eCollection 2022.

Authors

Linlin Wang^{1

2}, Fuyuan Zhang¹, Kuo Zeng³, Wenwen Dong^{1

2}, Huiya Yuan^{1

2}, Ziwei Wang¹, Jin Liu¹, Jiaqing Pan¹, Rui Zhao^{1

2}, Dawei Guan^{1

2}

Affiliations

¹ Department of Forensic Pathology, China Medical University School of Forensic Medicine, Shenyang, China.
² Liaoning Province Key Laboratory of Forensic Bio-evidence Science, Shenyang, China.
³ Institute of Evidence Law and Forensic Science, China University of Political Science and Law, Beijing, China.

Abstract

Introduction: Bodies recovered from water, especially in the late phase of decomposition, pose difficulties to the investigating authorities. Various methods have been proposed for postmortem submersion interval (PMSI) estimation and drowning identification, but some limitations remain. Many recent studies have proved the value of microbiota succession in viscera for postmortem interval estimation. Nevertheless, the visceral microbiota succession and its application for PMSI estimation and drowning identification require further investigation.

Methods: In the current study, mouse drowning and CO₂ asphyxia models were developed, and cadavers were immersed in freshwater for 0 to 14 days. Microbial communities in the liver and brain were characterized via 16S rDNA high-throughput sequencing.

Results: Only livers and brains collected from 5 to 14 days postmortem were qualified for sequencing. There was significant variation between microbiota from liver and brain. Differences in microbiota between the cadavers of mice that had drowned and those only subjected to postmortem submersion decreased over the PMSI. Significant successions in microbial communities were observed among the different subgroups within the late phase of the PMSI in livers and brains. Eighteen taxa in the liver which were mainly related to Clostridium_sensu_stricto and Aeromonas, and 26 taxa in the brain which were mainly belonged to Clostridium_sensu_stricto, Acetobacteroides, and Limnochorda, were selected as potential biomarkers for PMSI estimation based on a random forest algorithm. The PMSI estimation models established yielded accurate prediction results with mean absolute errors ± the standard error of 1.282 ± 0.189 d for the liver and 0.989 ± 0.237 d for the brain.

Conclusions: The present study provides novel information on visceral postmortem microbiota succession in corpses submerged in freshwater which sheds new light on PMSI estimation based on the liver and brain in forensic practice.

Keywords: aquatic habitat; decomposition; internal organ; microbial community; postmortem submersion interval.