Scientists Have Identified The Offending Enzyme Which Causes That "BO" Smell

There's more to BO than just being dirty, you need the perfect combination of bacteria and one special enzyme. Giulio_Fornasar/Shutterstock

Our bodies are amazing, but unfortunately as animals with a strong sense of smell we’re not always delighted with the olfactory signals they put out. If you’ve ever been to a festival or found yourself bedbound beyond the limits of that 24-hour antiperspirant, chances are you’ve experienced what’s (un)popularly known as “body odor”. While all too recognizable on your morning commute, the exact origins of this common perfume had eluded scientists, but new research published in the journal Nature has pinpointed the offending enzyme.

Our bodies are covered in bacteria, but only a few of these have been associated with smells. Now, researchers from the University of York in collaboration with Unilever scientists have discovered a “BO enzyme” that is found only within the bacteria linked to odorous armpits. The enzyme, called C-T lyase, facilitates the production of thioalcohols, a common culprit in BO, from a few strains of bacteria belonging to the Staphylococcus family.

"Solving the structure of this 'BO enzyme' has allowed us to pinpoint the molecular step inside certain bacteria that makes the odor molecules,” said co-first author Dr Michelle Rudden, from the University of York's Department of Biology, in a statement. “This is a key advancement in understanding how body odour works and will enable the development of targeted inhibitors that stop BO production at source without disrupting the armpit microbiome."

We often associate bacteria with illness, but these BO-producing bacteria are part of your natural skin microbiome. The most common offender for getting a bit wiffy was found to be Staphylococcus hominis, a common and harmless resident on the skin of animals including humans.

The research also revealed that this "BO enzyme" was present in S. hominis long before humans came along, meaning that our primate ancestors were likely strutting about exuding the strong stuff. While unpleasant to the modern nose, strong smells in wild animals often serve an important purpose in societal communication. Fortunately, we’ve since evolved elaborate language that negates the need for communicative underarms, but for our early ancestors a bit of BO could say a thousand words.

"This research was a real eye-opener,” said Unilever co-author Dr Gordon James. “It was fascinating to discover that a key odour-forming enzyme exists in only a select few armpit bacteria – and evolved there tens of millions of years ago."


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