Oral bacteria create mouth ‘fingerprint’

A new study reveals that bacteria in the human mouth – particularly those nestled under the gums – are as powerful as a fingerprint at identifying a person’s ethnicity.

Scientists identified a total of almost 400 different species of microbes in the mouths of 100 study participants belonging to four ethnic affiliations: non-Hispanic blacks, whites, Chinese and Latinos.

Only 2% of bacterial species were present in all individuals – but in different concentrations according to ethnicity – and 8% were detected in 90% of the participants.

Researchers found that each ethnic group in the study was represented by a ‘signature’ of microbial communities.


Purnima Kumar, associate professor of periodontology at the Ohio State University and senior author of the study, said: ‘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, which is why your dentist stresses brushing and flossing. Can  your genetic make-up play a similar role? The answer seems to be yes, it can. No two people were exactly alike. That’s truly a fingerprint.’

Professor Kumar used a DNA deep-sequencing methodology to obtain an unprecedented in-depth view of these microbial communities in their natural setting.

When the scientists trained a machine to classify each assortment of microbes from under the gums according to ethnicity, a given bacterial community predicted an individual’s ethnicity with 62%. The classifier identified African Americans according to their microbial signature correctly 100% of the time.

The findings could help explain why people in some ethnic groups, especially African Americans and Latinos, are more susceptible than others to develop gum disease.

The research also confirms that one type of dental treatment is not appropriate for all, and could contribute to a more personalised approach to care of the mouth.

She added: ‘The most important point of this paper is discovering that ethnicity-specific oral microbial communities may predispose individuals to future disease.’

Though it’s too soon to change dental practice based on this work, she said the findings show that ‘there is huge potential to develop chair-side tools to determine a patient’s susceptibility to disease’.

The research is published in the 23 October 2013 issue of the journal PLOS ONE

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