"Your body is coated with bacteria inside and out," says CU-Boulder assistant professor Noah Fierer in a video on YouTube. "You're basically a walking microbial habitat. And we found that the diversity of bacteria just on the skin surface is really pretty incredible. You habor hundreds of different bacteria species just on your palm, for example. We've also found that everybody is pretty unique. So of those let's say hundred or so bacteria species, very few are of them are shared between individuals."
What Fierer and his colleagues have demonstrated in a new study is that the distinctive combination of bacteria each of us carries and distributes can be used to help identify what we've touched.
Such work may one day help link individuals to malicious computer use or other crimes.
The study, "Forensic identification using skin bacterial communities," appears in the March 15 Proceedings of the National Academy of Sciences. It describes how the researchers swabbed bacterial DNA from the keys of three personal computers and matched them to the bacteria on the fingertips of the owners of the keyboards. It also details a similar test conducted on computer mice that had not been touched for over 12 hours.
The study indicates that the technique is 70% to 90% accurate and Fierer expects that accuracy will improve as the technique is refined. Until accuracy is extremely high, the technique is most likely to be useful as a way to augment more established forensic techniques, like fingerprinting and DNA identification.
"There's still a lot of work we need to do to assess the validity of the technique and how well we can recover bacteria from surfaces and how well we can match objects to the individual how touched that object," Fierer explains in the video.
In a University of Colorado at Boulder news release, Fierer said that the new technique raises bioethical issues, including privacy. "While there are legal restrictions on the use of DNA and fingerprints, which are 'personally-identifying,' there currently are no restrictions on the use of human-associated bacteria to identify individuals," he said.
Fierer was not immediately available to comment.