Find the culprit by microbe prints?
Scientists at the University of Colorado at Boulder, working under the leadership of Rob Knight, argue that identifying a unique set of bacteria that inhabit human skin and remain on all surfaces he touches (for example, a computer keyboard) will help improve the efficiency of criminologists in the future.
The results of the work were published on March 15 in the preliminary on-line version of the journal The Proceedings of the National Academy of Sciences in the article "Forensic identification using skin bacterial communities".
The researchers isolated bacterial DNA from numerous samples obtained by processing three computer keyboards, and sequenced more than 1,400 copies of bacterial ribosomal DNA from each sample, which allowed them to identify individual bacterial species included in each of the samples. After that, by comparing the data obtained with the results of DNA sequencing of bacteria inhabiting the skin of the keyboard owners, they were able to accurately determine their affiliation. After that, the authors analyzed the DNA of bacteria that lived on the surface of computer mice belonging to nine individuals, and compared the data obtained with the results of DNA analysis of bacterial communities found on the skin of the hands of 270 people who had never touched any of the nine mice. As a result, it turned out that the bacterial community found on the surface of each of the mice was much closer to the microbiome of their hosts than to any of the microbiomes from the analyzed database.
The authors note that their proposed approach is still at the initial stages of development, but over time it may acquire the same value for forensic specialists as fingerprinting and DNA analysis, which are currently widely used. Moreover, a smear from the surface of the skin contains at least 100 times more bacterial DNA than human genetic material. This means that a completely insignificant amount of biological material that can be obtained from the most fuzzy and blurred fingerprint can provide specialists with a lot of important information.
According to Stanford University professor David Relman, the idea of using microbial "fingerprints" is not new. Scientists have already wondered about the possibility of identifying a person by identifying unique strains of Escherichia coli inhabiting the digestive tract. Such ideas have been in the air for a long time, but their implementation into reality has become possible only recently, thanks to the advent of fast and relatively inexpensive DNA sequencing methods, which allowed scientists to create a library of bacterial "barcodes" - short sequences of specific bacterial DNA that quickly identify different types of bacteria.
The results of several recent studies carried out within the framework of the Human Microbiome Project have shown that bacterial communities inhabiting the skin of different people, as well as the skin of different parts of the body of the same person, differ significantly from each other. However, recent data indicate that even residual amounts of microflora of the skin of the hands remaining on objects after touching retain signs of individuality.
The researchers note that to date there are still no answers to many questions regarding the potential accuracy of the approach they are developing, and the results they have obtained are only a confirmation of the concept.
On the one hand, it is unclear whether it is possible to obtain a fingerprint of the human microbiome after another individual has touched the object under study. Another ambiguity lies in finding out the real stability of the human microbiome, which may be affected by taking antibiotics.
However, the complexity of the issue gives it great value, which the results of DNA analysis and fingerprint examination do not have. For example, the human microbiome not only identifies his personality, but also provides information about his diet, place of residence and work, and possibly other informative factors.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of TechnologyReview: Fingertip Bacteria: A Promising Forensic Tool.
18.03.2010