Bach Seat

Researchers have developed a new technique to identify individuals by the hand bacteria they leave behind on their personal computers keyboard and computer mice. Researchers at the University of Colorado (CU) at Boulder have shown that “personal” bacterial communities living on the fingers and palms of individual computer users that were deposited on keyboards and mice closely matched the bacterial DNA signatures of users.

The development of the technique is continuing, but it could offer a way for forensics experts to independently confirm the accuracy of DNA and fingerprint analyses, says CU-Boulder Assistant Professor Noah Fierer, chief author of 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, ” … we think the technique could eventually become a valuable new item in the toolbox of forensic scientists.”

The team used gene-sequencing techniques to match bacteria DNA swabbed from individual keys on computers to bacteria on the fingertips of keyboard owners. Fierer said in the article that 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. 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 researchers were able to successfully match the owner’s palm bacteria and the owner’s mouse from a group of 270 randomly selected samples.

The study showed the new technique is about 70 to 90 percent accurate, a percentage that likely will rise as the technology becomes more sophisticated, said Fierer. The CU-Boulder team used a “metagenomic” survey to simultaneously analyze all the bacteria on the fingers, palms, and computer equipment, said co-author Rob Knight. The effort involved isolating and amplifying tiny bits of microbial DNA, then building complementary DNA strands with a high-powered sequencing machine that allowed the team to identify different families, genera, and species of bacteria from the sample.

Another reason the new technique may prove valuable to forensic experts is that unless there is blood, tissue, semen, or saliva on an object, it’s often difficult to obtain sufficient human DNA for forensic identification, said Fierer. But given the abundance of bacterial cells on the skin surface, it may be easier to recover bacterial DNA than human DNA from touched surfaces, they said. “Our technique could provide another independent line of evidence.”

Once further research is completed, Frier says the new technique may be useful for linking objects to users in cases where clear fingerprints cannot be obtained – from smudged surfaces, fabrics and highly textured materials, he said. The new technique would even be useful for identifying objects touched by identical twins since they share identical DNA but they have different bacterial communities on their hands.

The study was published March 15, 2010, in the Proceedings of the National Academy of Sciences. Co-authors included Christian Lauber and Nick Zhou of CU-Boulder’s Cooperative Institute for Research in Environmental Sciences, 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.

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Fierer states that this new technique brings up bioethical issues to consider, 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. “This is an issue we think needs to be considered.”

It would be my recommendation that firms get ahead of this issue and review their employee privacy policies to deter the “expectation of privacy” until the courts decide if bacteria growing outside of an individual is eligible to be classified as “personally identifiable information” (PII).

Ralph Bach has been in IT long enough to know better and has blogged from his Bach Seat about IT, careers, and anything else that catches his attention since 2005. You can follow him on LinkedIn, Facebook, and Twitter. Email the Bach Seat here.