Humans regularly slough off skin cells as we move through our environment but did you know we shed much more than this?
We know that dead skin cells scatter onto our couch, our bed, and plush toys (these skin cells of course, are what dust mite live off) but new research shows that everyday we are emitting the very bugs which we call our microbiota, and not just the ones living on our skin.
We have evolved with masses of microbes, living in and on us, in a (usually) harmonious and symbiotic relationship.
While probiotic research investigates the potential health effects of just a few of the hundreds of species in our guts, there's a whole other world of microbes living on our skin, and exciting new research shows that we shed and share many of these microbial passengers with our environment as we move through our daily lives.
As we interact with our environment, we emit about a million particles every hour, many of which are the bugs which live both inside us and on our skin. As we shed skin cells, breathe, touch various objects and other humans, these microbes shed into the air around us and onto surfaces we contact. Previous research has shown that humans share microbial species and strains with their pets, but a new study shows that we share these microbes with the local environment with which we interact (or indeed, is this one way in which these microbes colonise other beings and travel to other locations?)
In a unique open study at the University of Oregon, volunteers were asked not to shower, were dressed shorts and tank tops, and were placed in specially-isolated sterile chambers with sensitive sampling equipment to collect microbes. These were then catalogued and compared to other volunteers. The experiment was repeated after 6 months and bacterial cloud shedding results compared to initial samples from each individual and between individuals.
All eleven subjects were free of disease symptoms at the time of sampling, had not taken antibiotics for at least 4 months, and were between the ages of 20 and 33.
Microbes were isolated from all areas of the body including our skin, nose, mouth, gut, and our genital respiratory tracts, revealing that although microbes prefer to reside in a usual location, we emit them into the surrounding environment on a regular basis from all areas of the body.
What the researchers found was quite surprising. The microbial clouds were unique in 8 of the 11 subjects of the study. In other words, a single individual could be identified by their unique bacterial fingerprint.
The researchers propose that further work might herald a use in forensic investigations. That is, to detect the recent presence of an individual at an indoor location, although the researchers admit that the results would be diluted in crowds of people, in a large indoor space, by increased airflow, or after a longer period of time.
Certainly though, this experiment sheds light on both the individuality of our microbial friends, and the way in which they may transfer between humans who come into regular casual contact, rather than previously thought intimate association.
Meadow JF, Altrichter AE, Bateman AC, et al. Humans differ in their personal microbial cloud. Peer J 2015 Sep 22;3:e1258. [Full text]