Personal microbial cloud can help identify strangers

Will you believe that strangers sitting in a chamber can be identified within four hours just by analysing their "microbial cloud signature" - the unique combinations of bacteria that they emit in the air as they speak or breathe? Researchers believe so.

To test the individualised nature of the personal microbial cloud, University of Oregon researchers sequenced microbes from the air surrounding 11 different people in a sanitised experimental chamber.

The study found that most of the occupants sitting alone in the chamber can be identified within four hours.

"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," explained lead author and post-doctoral researcher James F Meadow.

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 an 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 emerged from two different studies and more than 14 million sequences representing thousands of different types of bacteria found in the 312 samples from air and dust from the experimental chamber.

The results demonstrate the extent to which humans possess a unique "microbial cloud signature".

The striking results were driven by 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.

The research sheds light on the extent to which we release our human microbiome to 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," the authors concluded in the open-access journal PeerJ.