Changes in the Microbiome at the Onset and End of Decomposition

Abstract

Decomposition is a rapidly evolving process that is dependent on various environmental factors such as climate, temperature, insect activity, large vertebrate scavenging, and microbial activity. Although other factors such as body weight and time have been evaluated, microbial activity should be considered as another major component in the decomposition process. This study was designed to investigate the microbiome and potential bacterial succession using two different DNA extraction methods, classic microbiologic techniques and 16S ribosomal sequencing at the onset and end of decomposition. Differences were observed between the bacterial phyla found on Day 1 versus Day 6. Among the various phyla, several different bacterial species were observed such as Kurthia gibsonii, K. sibirica, Staphylococcus sciuri, S. lentus, and Serratia marcescens. An interesting change in the phyla present was observed for Day 6. None of the bacterial samples collected on any of the anatomical sites were identified in the phylum Firmicutes. In fact, most of the bacteria collected from the mouth, nose, and genitals were identified in the phyla Actinobacteria and Proteobacteria. Two different bacterial species, Myroides odoratus and Leucobacter aridicollis were present in the two phyla at Day 6 that were not observed at the onset of decomposition. Likewise, many of the bacterial species present at Day 1 were not observed in Day 6. The difference in bacterial diversity observed at the onset and end of decomposition suggest that a timeline or bacterial succession could be developed that could support post-mortem interval determinations.