The oral bacteria that reside in the mouth of every individual are as unique to each person as a fingerprint and may be heavily determined by ethnicity.  In a recent study, scientists identified 398 different species of microbes from bacteria samples of 100 participants that represented four different ethnicities including white, non-Hispanic black, Chinese, and Latino.  Only 2 percent of the microbial species were found in every participant while each ethnic group had “signature” microbial communities.

According to Purnima Kumar, associate professor of periodontology at Ohio State University and senior author of this study, “This is the first time it has been shown that ethnicity is a huge component in determining what you carry in your mouth.  We know that our food and oral hygiene habits determine what bacteria can survive and thrive in our mouths . . . Can your genetic makeup play a similar role?  The answer seems to be yes, it can.”  She adds, “No two people were exactly alike.  That’s truly a fingerprint.”

The Study

For the study, the researchers collected bacteria samples from the saliva, tooth surfaces, and under the gums of the participants.  The samples were analyzed with a DNA deep sequencing methodology because mouth bacteria will not grow in a laboratory dish, and the researchers also trained a machine to classify each microbial community according to ethnicity.  Using only bacteria from under the gums, this machine was able to determine ethnicity with 62 percent accuracy, positively identifying African Americans with complete accuracy, Latinos at 67 percent accuracy, and whites with 50 percent accuracy.  When the researchers studied the microbes from all areas of the mouth, surrogate communities of bacteria were found in 80 percent of the participants within each ethnic group.


The results of this study provide insight into why people of some ethnic groups are more likely than others to develop gum disease.  This study also shows that the same dental treatment may not be appropriate for every patient and that dentists may need to take a more personalized approach to providing oral care.  Over 60 percent of oral bacteria found in humans have not been adequately studied or identified and the power of bacteria is still somewhat misunderstood, yet this study suggests that microbes in the mouth can predispose people to certain diseases.

“The most important point of this paper is discovering that ethnicity-specific oral microbial communities may predispose individuals to future disease,” according to Kumar.  “There is huge potential to develop chair-side tools to determine a patient’s susceptibility to disease.”

The results of this study are published in the journal PLOS ONE.