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New biometric identifier: hand bacteria

Published 16 March 2010

Each individual has a “personal” bacteria communities living on the fingers and palms of individual computer users; members of these communities are deposited on keyboards, mice and other things we touch; the link between the bacterial communities and the bacterial DNA signatures of individuals may soon become a tool in forensic identification

Forensic scientists may soon have a valuable new item in their toolkits — a way to identify individuals using unique, telltale types of hand bacteria left behind on objects like keyboards and computer mice, says a new University of Colorado at Boulder study.

The CU-Boulder study showed that “personal” bacterial communities living on the fingers and palms of individual computer users that were deposited on keyboards and mice 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 forensics experts to independently confirm the accuracy of DNA and fingerprint analyses, says CU-Boulder Assistant Professor Noah Fierer, chief author on the study.

Each one of us leaves a unique trail of bugs behind as we travel through our daily lives,” said Fierer, an assistant professor in CU-Boulder’s ecology and evolutionary biology department. “While this project is still in it’s preliminary stages, we think the technique could eventually become a valuable new item in the toolbox of forensic scientists.”

The study was published 15 March in the Proceedings of the National Academy of Sciences. Co-authors on the PNAS study included Christian Lauber and Nick Zhou of CU-Boulder’s Cooperative Institute for Research in Environmental Sciences, or CIRES, Daniel McDonald of CU-Boulder’s department of chemistry and biochemistry, Stanford University Postdoctoral Researcher Elizabeth Costello and CU-Boulder chemistry and biochemistry Assistant Professor Rob Knight.

Using powerful gene-sequencing techniques, the team swabbed bacterial DNA from individual keys on three personal computers 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 said.

In a second test, the team swabbed nine keyboard mice that had not been touched in more than twelve 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