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Scientists Can Tell Your Ethnicity by the Germs in Your Mouth

Everyone has a unique mouth. In each, a diverse microbial community thrives, in the plaque, the spit and under the gums. The bacterial cocktail can be a little bit different from one to another. It seems that genetics play an important role in determine what type of communities you are carrying around your teeth. A new research from The Ohio State University says that various ethnicities have different oral bacterial profiles and this new finding could affect the treatment of oral disease.

100 participants took part in the study and they are from four ethnic backgrounds, Caucasian, African American, Chinese and Latino. There are almost 400 distinct species thriving in the mouths, however, only 2% of bacterial species identified were present in each individual studied. In addition, approximately 8% of species were shared by 90% of the participants. Different ethnic group showed different pattern of bacteria, particularly under the gums.


Venn Diagram of Ethnicity Specific Bacteria. *Image source: Mason et al.

“This recommends that host genotype affects the microbial community to an even greater extent than shared environment,” the author notes, “”Nature” seems to win over “nurture” in shaping this community.”

The researchers were successful in developing an algorithm to predict an individual’s ethnicity according to bacteria from under their gums with an accuracy of 62%. This algorithm was capable of classifying the bacterial communities of African American subjects 100% of the time, however, it was unable to be as accurate for other ethnicities.


Mouth Bacteria Distribution. Left: Bacteria signature in plaque under the gums. Right: Bacteria in the saliva. Each color is corresponding to an ethnicity. *Image source: Mason et al., 2013.

“We are aware that what bacteria can survive and thrive in our mouth is dependent on our food and oral hygiene habits, and this is why our dentist stress brushing and flossing,” said senior author Pumima Kumar, an associate professor at the OSU dental college. “Is your genetic makeup playing a similar role? The answer is yes.”

If everyone has a different bacterial community hanging out in the mouth, it might impact how we treat oral disease. Researchers will need to examine whether certain microbial communities may predispose people to various diseases. It could also influence disease therapies that call for rebuilding healthy bacteria in the mouth, since in the past, dentists assumed that healthy bacteria communities were the same for every person.

Source: Popular Science.