Telltale bacteria

Forensic scientists may soon be able to identify individuals using unique, telltale types of hand bacteria left behind on objects such as keyboards and computer mice.

According to researchers at the University of Colorado at Boulder, ’personal’ bacterial communities living on the fingers and palms of individual computer users that were deposited on PC equipment matched the bacterial DNA signatures of users much more closely than those of random people.

While the development of the technique is continuing, it could provide a way for forensic experts to independently confirm the accuracy of DNA and fingerprint analyses, said Noah Fierer, CU-Boulder assistant professor.

Using powerful gene-sequencing techniques, the team swabbed bacterial DNA from individual keys on three PCs and matched them up to bacteria on the fingertips of keyboard owners, comparing the results to swabs taken from other keyboards never touched by the subjects. The bacterial DNA from the keys matched much more closely to bacteria of keyboard owners than to bacterial samples taken from random fingertips and from other keyboards, Fierer added.

In a second test, the team swabbed nine keyboard mice that had not been touched in more than 12 hours and collected palm bacteria from the mouse owners. The team compared the similarity between the owner’s palm bacteria and owner’s mouse with 270 randomly selected bacterial samples from palms that had never touched the mouse. In all nine cases, the bacterial community on each mouse was much more similar to the owner’s hand.

The team sampled private and public computers at CU-Boulder, as well as hand bacteria collected from a variety of volunteers on campus. The study showed the new technique is about 70 to 90 per cent accurate, a percentage that is likely to rise as the technology becomes more sophisticated, said Fierer.