Signature of oral bacteria identifies ethnicity

By - Bad Breath Expert

SUMMARY:  The bacteria in the human mouth knows a lot about us, including our ethnicity. Find out how these microbes contain a 'fingerprint.'

Posted: November 19, 2013

oral bacteria ethnicities

Your mouth has a signature. According to a new study, the oral bacteria in the human mouth is so personalized that it identifies a person's ethnicity.

The research, led by Purnima Kumar who is the associate professor of periodontology at Ohio State University and senior author of the study, analyzed nearly 400 different species of microbes in the mouths of 100 participants in four ethnic groups: Chinese, non-Hispanic blacks, whites and Latinos. Using a DNA deep sequencing method to achieve an in-depth view of the microbial communities in their natural environment, Kumar discovered that each person had their own 'fingerprint' while sharing microbes with members of their ethnicity.

"This is the first time it has been shown that ethnicity is a huge component in determining what you carry in your mouth," Kumar said in the Ohio State press release. "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 makeup play a similar role? The answer seems to be yes, it can."

Only 2 percent of bacterial species were present in all subjects, and each individual had different concentrations based on their ethnicity. In nine out of ten participants, 8 percent of microbes were detected. Beyond that, the researchers found that each ethnic group in the study was represented by a "signature" of shared microbial communities.

"No two people were exactly alike," Kumar told the source. "That's truly a fingerprint."

Bacteria live in communities called biofilms in which they interact with each other and the immune system. In this way, keeping these biofilms healthy is a key to overall health.

Interestingly enough, the scientists programmed a machine to classify each group of microbes. For African Americans, the communities of bacteria showed a prediction likelihood of 65 percent, 33 percent for Chinese, 45 percent for Caucasians and 47 percent for Latinos. The bacteria under the gums proved particularly effective in pinpointing a person's ethnicity. This made sense to Kumar, since the bacteria below the gums are the least likely to be disturbed by environmental variations in the mouth, such as food, tobacco and toothpaste. 

The DNA sequences came out to 398 overall units, with an average of around 150 various species per person.

The bacteria in the human mouth is somewhat like the ocean depths - only a small percentage has been explored. Less than 40 percent of the microbes in the mouth have been studied, classified or even named because they won't grow in a laboratory dish. For this reason, Kumar's team identified the different species by sequencing their DNA.

Importantly, the biofilms are not strictly good or bad for the health of mouth. They have the ability to do both, and Kumar suggests that as long as we harness their good side, by brushing, flossing and visiting the dentist regularly, we can steer them in the right direction.

Nature vs. nurture
According to the National Institute of Dental and Craniofacial Research, African Americans and Hispanics run a greater risk for oral health issues, including cavities and gum disease. Scientists link this to the socio-economic levels, in which lower-income families tend to indicate higher percentages of infections, dental caries and other problems left untreated. 

At the same time, however, Kumar posits that the genetic make-up of members belonging to these ethnic group may also play a role, carrying the potential to further explain why African Americans and Latinos are more susceptible than others to develop gum disease.

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

To nurture the healthy effects of the microbes and prevent cavities, dentists emphasize that you should stay proactive about your dental habits. Brushing twice each day and flossing once are crucial in maintaining a clean mouth. 

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