Team Identifies Bacteria That Play Key Role in Armpit Odor; Develops Enzyme to Kill It without Harming Other Beneficial Bacteria

Yomiuri Shimbun file photo
The entrance of Osaka Metropolitan University

Afraid you might “offend” when you are out in public on a hot day? There may be relief in store to those prone to emitting an offensive armpit odor.

A research team led by Osaka Metropolitan University recently announced it has succeeded in identifying the bacteria that cause armpit odor and has synthesized an enzyme that kills it, raising hope for an effective treatment.

The team, which included the Institute of Medical Science of the University of Tokyo and Mandom Corp., an Osaka-based major cosmetics maker, recently published its findings in an international scientific journal.

Armpit odor results when bacteria on the surface of the skin dissolve substances secreted by the apocrine glands, a kind of sweat gland located under the skin of the armpit. This produces the bad odor, which is believed to be a concern for about 10% of Japanese people.

The Osaka Metropolitan University team members, led by Dr. Miki Watanabe and Assistant Prof. Miho Uematsu, examined the types and quantities of compounds found in the sweat of 20 adult men, then analyzed the genes of armpit bacteria using a supercomputer.

Meanwhile, a Mandom researcher extracted substances that are abundant in the sweat of those whose odor was deemed “strong,” and searched for bacteria that genetically can dissolve those substances.

The result was that they narrowed the “culprit” down to a number of types of bacteria, eventually finding that one strain of persistent staphylococci that plays a key role in causing armpit odor.

In addition, the team identified the genes of a bacteria-attacking virus, known as a bacteriophage, then succeeded in synthesizing an enzyme which can be used as a weapon.

When exposed to the many types of bacteria found on the skin, the enzyme selectively killed only the kind that causes an odor. It left unharmed other kinds of bacteria that play such roles as maintaining moisture in the skin.

“There are no effective medicines to treat bad armpit odor, and the only options have been to use drugs to minimize sweating or to surgically remove the apocrine glands in the armpits,” said Takafumi Eto, president of the Japan Organization of Clinical Dermatology.

“There are people who worry about it so much that it hampers their everyday lives. If [the enzyme] can be used in medicinal form, I’m sure it will make a lot of people happy.”