Just like Pig-Pen from the Peanuts cartoons, the human body spews a cloud, but instead of dirt it contains millions of microorganisms.
“It turns out that that kid is all of us,” said James Meadow, a microbial ecologist who led research about the microbes shadowing us during postdoctoral work at the University of Oregon. “It’s just a microscopic cloud that’s really hard to see.”
Scientists have discovered that we each give off millions of bacteria from our human microbiome to the air around us every day, and that cloud of bacteria can be traced back to each individual. New research focused on the personal microbial cloud — the airborne microbes we emit into the air — examined the microbial connection we have with the air around us. The findings demonstrate the extent to which humans possess a unique “microbial cloud signature.”
In a story for National Geographic last year, Ed Yong described the way that each movement propels bacteria from the body into the world: “I touch the desk, the light switch, the coffee mug, and the microbes on my hands now coat those objects. I absent-mindedly swish my foot across the floor, and I leave microbes there too. I scratch my head, ejecting a cloud of microbes into the air.”
“When a new family moves into a new home, within 24 hours their microbial signature had been imposed upon the house. Pretty much every space in the house is now identifiable,” said Jack Gilbert, an ecology professor at the University of Chicago and the leader of the Home Microbiome Study.
To test the individualized nature of the personal microbial cloud, University of Oregon researchers sequenced microbes from the air surrounding 11 different people in a sanitized experimental chamber. The study found that most of the occupants sitting alone in the chamber could be identified within 4 hours just by the unique combinations of bacteria in the surrounding air. The findings appear in the September 22nd issue of PeerJ.
The marked results were driven by several groups of bacteria that are omnipresent on and in humans, such as Streptococcus, which is commonly found in the mouth, and Propionibacterium and Corynebacterium, both commonly found on the skin. While these common human-associated microbes were detected in the air around all people in the study, the authors found that the different combinations of those bacteria were the key to distinguishing among individual people.
“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,” said lead author James F. Meadow, a postdoctoral researcher formerly from the Biology and the Built Environment Center at 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 concluded.
The research illuminates the extent to which we release our human microbiome into our surrounding environment, and might help understand the mechanisms involved in the spread of infectious diseases in buildings. The results also suggest potential forensic applications, for example to identify or determine where a person has been, though it is unclear whether individual occupants can be detected in a crowd of other people.