An Investigation of Intrinsic and Extrinsic Factors that Influence Soil Microbial Succession During Human Decomposition

• NCJ Number: 309999
• Author(s): Allison Mason; Todd B. Reynolds; Sindhu Jagadamma
• Date Published: 2022
• Length: 225 pages
• Grant Number(s): 2018-DU-BX-0180
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Thesis/Dissertation
• Award: The Impact of Drugs on Human Decomposition and the Postmortem Interval: Insect, Scavenger and Microbial Evidence

Annotation

This study investigates factors that influence soil microbial succession during human decomposition.

Abstract

This dissertation shows that soil microbial succession during decomposition is impacted by both intrinsic and extrinsic factors. The study provides an important framework for understanding the ecology of human and vertebrate decomposition in terrestrial ecosystems. The researcher had three objectives: (1) evaluation of the effects of intrinsic factors on soil microbial succession, (2) evaluation of the effects of extrinsic factors on soil microbial succession, and (3) evaluation of soil microbial functional succession during decomposition. Two separate field studies were conducted. The first observed the early stages of decomposition of 19 subjects, while the second observed a longer-term decomposition of three subjects. All subjects decomposed on the soil surface at the University of Tennessee Anthropology Research Facility. Body mass index affected soil chemical response and microbial succession, making it a factor of interest for future investigations. The study also used metatranscriptomics to show that microbial gene expression shifted during decomposition and was still impacted following one year. Decomposer organisms play a vital role in terrestrial nutrient cycling, breaking down complex organic compounds and providing nutrients for primary producers. The ultimate aim of this body of research was to improve understanding of soil microbial succession during decomposition by assessing these knowledge gaps. Microbial communities and other decomposers associated with a vertebrate carcass, or the “necrobiome”, are critical for degradation and recycling of soft tissues following vertebrate mortality. The impact of microbial decomposers in vertebrate decomposition has been shown with regard to soil microbial communities, where the presence of soil microbes impact decomposition rate and undergo succession.