Our Microbial Clouds

Turns out Charles Schultz was right. We all carry a cloud of microbes around with us, just like the Peanuts character Pig-Pen. Oregon researchers, publishing today in PeerJ, confirm our “personal microbial cloud” and determine that like fingerprints, no two are alike.

We know that our microbes (think germs) fill the air—it’s how colds, flu, and other diseases spread—but what is the diversity of these microbes beyond the pathogens that make us sick? There are many of the little critters; in fact, according to the paper we emit a million biological particles per hour! The team of scientists created a sanitized chamber to let people come in, one by one, to determine what makes up our clouds.

They discovered that several groups of bacteria that are ubiquitous on and in humans, such as Streptococcus, which is commonly found in the mouth, and Propionibacterium and Corynebacterium, both common skin residents, fill our personal microbial clouds. The trick is the combination of these bacteria within each cloud. Looking at these combinations, the team was able to identify people within the chamber by the airborne bacteria.

“We expected that we would be able to detect the human microbiome in the air around a person, but we were surprised to find that we could identify most of the occupants just by sampling their microbial cloud,” says lead author James F. Meadow, of the University of Oregon.

“Our results confirm that an occupied space is microbially distinct from an unoccupied one, and demonstrate for the first time that individuals release their own personalized microbial cloud,” the authors conclude in the paper’s abstract.

The research might help understand the mechanisms involved in the spread of infectious diseases in buildings, and also in forensic applications, for example to identify or determine where a person has been. There is one catch, however: it is unclear whether individual occupants can be detected in a crowd of other people (and not just a sanitized chamber). How do our clouds interact? If only Lucy and Charlie Brown had clouds like Pig-Pen, too, then maybe we’d know…

Image: Meadow et al. (2015), PeerJ: DOI10.7717/peerj.1258https://peerj.com/articles/1258/