(By Dr. Joseph D. Lim and Dr. Kenneth Lester Lim, BS-MMG, DDM, MSc-OI)
BAD BREATH comes from the interaction between two common oral bacteria.
The interaction leads to the production of a chemical compound that causes bad breath, according to researchers at Osaka University.
Why is this important? Well, for a start, understanding how the two bacteria work together to cause bad breath could be helpful in developing ways to treat or even prevent bad breath.
Given that bad breath is often associated with gum disease, treating the symptom early could also help prevent more serious damage in the future.
In a study published in mSystems, the Osaka University researchers found that bad breath is caused by volatile compounds that are produced when bacteria in the mouth digest substances like blood and food particles.
One of the smelliest of these compounds is methyl mercaptan (CH3SH) which is produced by microbes that live around the teeth and on the surface of the tongue. Little is known about which specific bacterial species are involved in this process.
“Most previous studies investigating CH3SH-producing oral bacteria have used isolated enzymes or relatively small culture volumes,” explains Takeshi Hara, the study’s lead author. “We aimed to create a more realistic environment in which to investigate CH3SH production by major oral bacteria.”
To do this, the researchers developed a large-volume anaerobic co-culture system that enabled them to test interactions between multiple different types of bacteria that live in the mouth. This method was able to test both direct, physical interactions among the bacteria, as well as whether these species could affect each other from a distance, for example by secreting active substances.
“The results were very intriguing,” says Masae Kuboniwa, the study’s senior author. “We found that Fusobacterium nucleatum produces large quantities of CH3SH in response to Streptococcus gordonii, another oral bacterium.”
By using stable isotope tracers and analyzing gene expression, the researchers showed that S. gordonii releases a substance called ornithine that prompts F. nucleatum to produce more of a molecule called polyamine.
Because F. nucleatum needs methionine to produce polyamine, this enhanced polyamine production activates its methionine salvage pathway, which in turn results in increased CH3SH production.
If that reads complicated, here’s how Hara explains it: “Taken together, these findings suggest that CH3SH production in the mouth is driven by the interaction between S. gordonii and F. nucleatum.”
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Dr. Joseph D. Lim, Ed. D., is the former Associate Dean of the College of Dentistry, University of the East; former Dean, College of Dentistry, National University; Past President and Honorary Fellow of the Asian Oral Implant Academy; Honorary Fellow of the Japan College of Oral Implantologists; Honorary Life Member of the Thai Association of Dental Implantology; and Founding Chairman of the Philippine College of Oral Implantologists. For questions on dental health, e-mail jdlim2008@gmail.com or text 0917-8591515.
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Dr. Kenneth Lester Lim, BS-MMG, DDM, MSc-OI, graduated Doctor of Dental Medicine, University of the Philippines, College of Dentistry, Manila, 2011; Bachelor of Science in Marketing Management, De la Salle University, Manila, 2002; and Master of Science (MSc.) in Oral Implantology, Goethe University, Frankfurt, Germany, 2019. He is an Associate Professor; Fellow, International Congress of Oral Implantologists; and Fellow, Philippine College of Oral Implantologists. For questions on dental health, e-mail limdentalcenter@gmail.com/PN
