Why do armpits stink? Study on bacteria that causes pungent body odor could help design effective deodorants

Staphylococcus hominis eats a sweat gland compound produced by humans, called Cys-Gly-3M3SH, and releases the foul-smelling thioalcohols as a byproduct

                            Why do armpits stink? Study on bacteria that causes pungent body odor could help design effective deodorants
(Getty Images)

A bacteria residing in the armpits is one of the main culprits behind the stinky body odor in humans. In a new study, scientists have discovered the microbe's secret weapon which helps it produce the pungent smell. These findings pave the way for effective deodorants or antiperspirants.

The bacteria is Staphylococcus hominis. It comes armed with an enzyme that produces the odor. "We’ve discovered how the odor is produced,” Prof Gavin Thomas, from the University of York and one of the authors of the study, told The Guardian. “What we really want to understand now is why," he added. The research is a collaboration between the University of York and a consumer goods manufacturer named Unilever. Human armpits host different kinds of microbes, some of whom are responsible for generating pungent-smelling molecules. Earlier, York scientists revealed that Staphylococcus hominis is majorly involved in this. It eats a compound produced by human sweat glands, called Cys-Gly-3M3SH, and releases the foul-smelling thioalcohols as a byproduct. But how exactly the microbe carries out this conversion was unknown until now.

To find out more, the team experimented on another armpit resident which reportedly does not produce any odor: Staphylococcus aureus. They got the organism to make the hominis' enzyme. Their results showed that the innocent bacteria began producing the foul-smelling thioalcohols. “Our noses are extremely good at detecting these thioalcohols at extremely low thresholds, which is why they are really important for body odor. They have a very characteristic cheesy, oniony smell that you would recognize. They are incredibly pungent," Thomas told The Guardian.

(University of York)


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

The researches trace the human origins of body odor to the primate ancestors. The bacteria colonized primates and produced the stinky compound, even before they made human armpits their home. Researchers suspect that this could suggest that body odor may have something to do with societal communication. "This discovery raises important questions about the role of odor production in the evolution of modern humans," the experts wrote in their study. “This research was a real eye-opener. It was fascinating to discover that a key odor-forming enzyme exists in only a select few armpit bacteria – and evolved there tens of millions of years ago," Unilever co-author Dr Gordon James said.

 “All we can say is this is not a new process. BO was definitely around while humans were evolving,” Thomas told The Guardian. “It’s not impossible to imagine these were important in the evolution of humans. Before we started using deodorants and antiperspirants, in the last 50 to 100 years, everyone definitely smelled.”

The study is published in Scientific Reports.

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