Asian Scientist (Oct. 31, 2013) – Bacteria in the human mouth – particularly those nestled under the gums – are as powerful as a fingerprint at identifying a person’s ethnicity, new research shows.
In the study, published in PLOS ONE, the scientists used DNA deep sequencing technology to identify a total of almost 400 different species of microbes in the mouths of 100 study participants belonging to four ethnic affiliations in the United States: non-Hispanic blacks, whites, Chinese and Latinos.
Samples of bacteria were collected from the saliva, tooth surfaces and under the gums of the study participants. Because more than 60 percent of bacteria in the human mouth have never been classified, named or studied because they won’t grow in a laboratory dish, the researchers identified the different species through their DNA sequence.
They found that only 2 percent of bacterial species were present in all individuals – but in different concentrations according to ethnicity – and 8 percent were detected in 90 percent of the participants. Beyond that, researchers found that each ethnic group in the study was represented by a “signature” of shared microbial communities.
“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 makeup play a similar role? The answer seems to be yes, it can,” said Associate Professor Purnima Kumar, the senior author of the study.
“No two people were exactly alike. That’s truly a fingerprint.”
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 personalized approach to care of the mouth.
“Nature appears to win over nurture in shaping these communities,” Kumar noted, because African Americans and whites had distinct microbial signatures despite sharing environmental exposures to nutrition and lifestyle over several generations.
The researchers had previously determined that smoking disrupts the healthy bacterial community in the oral cavity, giving disease-causing microbes easier access to the mouth.
Multiple diseases of the mouth are caused by bacterial infections, ranging from cavities to oral cancer. Although Kumar didn’t expect ethnicity to produce significant differences in the bacterial collection in the mouth, the patterns became clear during the DNA analysis.
The power of bacteria in the body remains misunderstood to some extent. Though many people are inclined to blame disease susceptibility on lifestyle and behavior, this work suggests that humans can be predisposed to certain disease risks solely because of the microbes that set up shop in their mouths.
“We underestimate these bugs and their power to do good and evil to us. As long as we harness their good side, we’re healthy,” Kumar said.
The article can be found at: Mason et al. (2013) Deep Sequencing Identifies Ethnicity-Specific Bacterial Signatures In The Oral Microbiome.
——
Source: Ohio State University; Photo: adonofrio (Biology101.org)/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
