University of Florida Health researchers have identified a new strain of bacteria called Streptococcus A12 that may keep “bad” bacteria in check and could lead to a way to developing an oral probiotic for preventing cavities.
The study published in the journal Applied and Environmental Microbiology says that A12 not only helps neutralize acid by metabolizing arginine in the mouth, it also often kills Streptococcus mutans.
When the environment in the mouth becomes more acidic, dental cavities or other disorders can develop, according to Robert Burne, Ph.D., one of the study’s authors.
“At that point, bacteria on the teeth make acid and acid dissolves the teeth. It’s straightforward chemistry,” Burne said. “We got interested in what activities keep the pH elevated.”
Their previous research found two main compounds in the mouth are broken down into ammonia, which helps neutralize acid in the mouth. These compounds are urea, which everyone secretes in the mouth, and arginine, an amino acid. Burne and Nascimento had also previously found that both adults and children with few or no cavities were better at breaking down arginine than people with cavities. Researchers knew bacteria were responsible for breaking down these compounds but needed to investigate which bacteria do this best, and how this inhibits cavities. Part of the answer is A12.
“Like a probiotic approach to the gut to promote health, what if a probiotic formulation could be developed from natural beneficial bacteria from humans who had a very high capacity to break down arginine?” said Burne. “You would implant this probiotic in a healthy child or adult who might be at risk for developing cavities. However many times you have to do that — once in a lifetime or once a week, the idea is that you could prevent a decline in oral health by populating the patient with natural beneficial organisms.”
A12 has a potent ability to battle a particularly harmful kind of streptococcal bacteria called Streptococcus mutans, which metabolizes sugar into lactic acid, contributing to acidic conditions in the mouth that form cavities. The UF researchers found that A12 not only helps neutralize acid by metabolizing arginine in the mouth, it also often kills Streptococcus mutans.
“Also, if A12 doesn’t kill Streptococcus mutans, A12 interferes with Streptococcus mutans’ ability to carry out its normal processes that it needs to cause disease,” Burne said. “If you grow them together, Streptococcus mutans does not grow very well or make biofilms, also known as dental plaque, properly.”
The researchers sequenced the entire genome of A12 and plan to turn this discovery into a tool to screen for people who are at a higher risk for developing cavities, in combination with other factors such as a patient’s diet and their oral hygiene habits.
“We may be able to use this as a risk assessment tool,”Marcelle Nascimento, D.D.S., Ph.D, one of the leaders on the project said. “If we get to the point where we can confirm that people who have more of this healthy type of bacteria in the mouth are at lower risk of cavities, compared to those who don’t carry the beneficial bacteria and may be at high risk, this could be one of the factors that you measure for cavities risk.”