An initial investigation into the ecology of culturable aerobic postmortem bacteria

• Swine carcasses were decomposed on Oahu, Hawaii, for 7 days during the summer.
• Bacteria from skin and larval masses were cultured on Standard Nutrient Agar.
• All postmortem bacterial communities differed by sampling location and time.
• Actinobacteria, Firmicutes, and Proteobacteria were the most common phyla.
• Larval masses were a reducing environment of neutral pH and high temperature.

Postmortem microorganisms are increasingly recognized for their potential to serve as physical evidence. Yet, we still understand little about the ecology of postmortem microbes, particularly those associated with the skin and larval masses. We conducted an experiment to characterize microbiological and chemical properties of decomposing swine (Sus scrofa domesticus) carcasses on the island of Oahu, Hawaii, USA, during June 2013. Bacteria were collected from the head, limb, and larval mass during the initial 145 h of decomposition. We also measured the pH, temperature, and oxidation–reduction potential of larval masses in situ. Bacteria were cultured aerobically on Standard Nutrient Agar at 22 °C and identified using protein or genetic signals. Carcass decomposition followed a typical sigmoidal pattern and associated bacterial communities differed by sampling location and time since death, although all communities were dominated by phyla Actinobacteria, Firmicutes, and Proteobacteria. Larval masses were reducing environments (~− 200 mV) of neutral pH (6.5–7.5) and high temperature (35 °C–40 °C). We recommend that culturable postmortem and larval mass microbiology and chemistry be investigated in more detail, as it has potential to complement culture-independent studies and serve as a rapid estimate of PMI.