May 22, 2006 — Deceased individuals supposedly "push up daisies," but a forthcoming study suggests human cadavers are more likely to support several species of white and yellow fungi.
The study is the first to describe in detail species of fungi obtained from human corpses. In the future, forensics experts may use the information during criminal investigations to determine an individual’s time of death.
Fungi -- which lack chlorophyll, leaves, and true roots and stems -- often form part of the natural decomposition process that recycles nutrients back into the food chain.
In this case, as lead author Kiyoshi Ishii told Discovery News, "The fungi feed on the dead."
Ishii and his colleagues analyzed two humans whose bodies were found decomposing in very different environments. The first was a corpse discovered lying face down on a concrete floor in an abandoned house. Police determined the body belonged to a 72-year-old man who had been missing for 10 months. The scientists observed yellow and white fungi on the deceased’s chest, abdomen and thighs, but little insect infestation, probably because the house was dry and isolated.
The second case study involved skeletal remains clad in a shirt and pants, which all were found in a forest next to a rope hanging from a tree branch. Forensics specialists determined the body belonged to a 50-60-year-old man who had hung himself at least 6 months before the body’s discovery. The scientists once again detected yellow and white fungi growing on the corpse.
Ishii, a biologist at Dokkyo University School of Medicine in Japan, and his team collected the fungi and incubated them in a laboratory. They identified several species including Gliocladium sp., a slimy counterpart to penicillin; Eurotium chevalieri, a fungus that can be bright yellow; and Eurotium repens, which is commonly found in soil. The Eurotium species dominated the collected samples.
Ishii explained that the white and yellow coloration is associated with the sexual stages for Eurotium fungi. The parasite produces threadlike filaments that terminate with circular, colorful structures called ascomata that are involved in reproduction. The fungi also produce colorful conidia, or asexual spores, which tend to form in the morning and germinate in the afternoon and evening hours.
Ishii said the environment in which a body lies, rather than the biochemistry of the individual or the manner of death, tends to dictate how much or how little fungi will colonize a cadaver. The team’s findings have been accepted for publication in the journal Legal Medicine.
Yuichi Chigusa, a medical parasitologist and entomologist at Dokkyo Medical University’s School of Medicine in Soka City, Japan, told Discovery News that fly larvae usually infest corpses within an hour to a half-day after the victims’ death, followed by Coleoptera (beetles) infestation and then fungal colonization. He is excited about the potential of fungi for further aiding detective work.
"I am surprised that fungus is a potential tool for determining post mortem intervals in cadavers without infestation of dipteran larvae and/or beetles," Chigusa said. "Therefore, I think it is very important that forensic pathologists, forensic entomologists and forensic mycologists cooperate in determining post mortem intervals during forensic analysis."
