Has anyone ever told you that it’s the little things that get you? Maybe you didn’t get in as much trouble as I did growing up but I have been told (usually by Mom) and have told (bad guys during my Cop life) that it is the little details, those fine points that even the most careful of us overlook that end up bringing all our nefarious plans crashing down on our heads. When I think of this I think of wearing gloves to hide your fingerprints. Or if you are a teenager in upstate New York in January, maybe watching out where you leave footprints in the snow when sneaking out at night. Oh I also got caught once when my folks asked me if I was power sliding my little VW down the street during an ice storm. When I denied that I would ever do something like that they gently showed me to the tire tracks that lead directly from the sideways prints on the street to my rear tires parked in the driveway: the little things.

I saw this little gem of an article and had to share. The next time you step onto a subway train, board an airplane, or take someone else’s phone to watch the newest annoyingly cute animal video think about this. “How your micro-biome can put you at the scene of the crime,” by Kai Kupferschmidt from Science Magazine.

Turns out that by the time we are 3 or 4 years we have gathered a unique set of bacteria from the environment we grow up in, and that mix remains fairly stable throughout our lives.

In 2010 a paper from the Proceedings of the National Academy of Sciences, researchers showed that bacterial DNA recovered from computer keyboards matched the micro-biomes found on their owners’ fingertips. The authors also sampled bacteria from nine computer mice and used the results to pick the owners out of a database of 270 micro-biomes.

Did anyone else just squirm a little when they read that?

A paper from 2015 identified that individuals have a theoretically unique microbial cloud that we carry with us, and deposit wherever we happen to go. We shed bacteria constantly spitting it from our mouths, breathing them out. Bacteria are so small that our clothes have no effect at containing them. Whenever we sit down or pick something up bacteria is deposited on that surface and it persists until the next person comes along. In the paper, researchers measured the bacterial cloud surrounding volunteers by placing them in a sanitized chamber and sampling the area around them. What they found was that they were able to identify individuals by this micro-biome we carry with us.

To apply this to the criminal world researchers swabbed places suspects are believed to have touched at crime scenes then sequence captured DNA in the laboratory. Once sequenced the profiles can be compared to a database and individual strains of bacteria can be identified. The mix, or unique ecosystem of different species of bacteria that are identified in the sample from the crime scene can then be compared to a known suspect sample to see if the two micro-biomes match.

In a practical evaluation, researchers in Illinois staged a fake break in then took samples from where the “burglars” handled things in the house. When the signatures from the suspects were reviewed the scientists not only could identify individual micro-biomes, but from residues in the samples determine the amount of alcohol one of the ‘suspects’ consumed each week and that one of them was on migraine medication. Even if the bacterial cloud could not be determined to be individual enough to identify a suspect to the exclusion of all others, (to date a sample size and technique has not been complete enough to try and take an identification based on bacteria to court), how great would it be if traits such as drug use, medication, or drinking habits could be used as leads in narrowing down the suspect pool?

Recently the J. Craig Venter Institute received a $900,000 grand from the National Institute of Justice to build a micro-biome database. That is a first step in evaluating whether or not bacteria can be used to identify someone. Practical application is a long way off.

Regardless I thought it interesting that when we now warn someone that it’s the little things that get you. We really mean it is the little things that get you, like your own bacteria, little.

Reference:

http://www.sciencemag.org/news/2016/03/how-your-microbiome-can-put-you-scene-crime

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