Unique microbial fingerprint from a hand smear test
Metagenomics benefits forensic science through microbial profiling By comparing the microbial profiles taken from a suspect’s hand and from an object found at a crime scene, it is pos- sible to assess the probability that the suspect was present there when the crime was committed. Humans, on average, have 150 types of microbes on their hands. This population is unique enough to be used as a means of identification. Moreover, microbial profiles show the origins of the tissue found in a trace. Peter de Knijff, professor of population and evolution genetics at Leiden University Medical Center’s department of Human Genetics, explains why this is such an exciting breakthrough. “The main problem in forensics is usually the lack of DNA. A human body cell contains just 6 picograms of DNA. The success of DNA testing depends largely on the amount of cell material on the surface and the time that has elapsed since it was last touched.” As De Knijff, who also heads the forensic lab for DNA testing (FLDO), points out, “microbial profiling is a totally different kettle of fish, because there’s usually plenty of bacteria available at the crime scene.”