Newly identified bacteria may lead to anti-cavity pills

A new strain of bacteria in the mouth that may keep bad microbes in check have been identified by scientists, that could lead to oral pills for prevention of cavities.
While developing an effective oral probiotic will require more research, a possible candidate organism has been identified - a previously unidentified strain of Streptococcus, currently called A12.
To maintain a healthy mouth, the oral environment must have a relatively neutral chemical makeup, or a neutral pH. When the environment in the mouth becomes more acidic, dental cavities or other disorders can develop, researchers said.
"At that point, bacteria on the teeth make acid, and acid dissolves the teeth," said Robert Burne from University of Florida.

Previous research has that urea, which everyone secretes in the mouth, and arginine, an amino acid are the two main compounds that are broken down into ammonia, which helps neutralise acid in the mouth.
Researchers had also previously found that both adults and children with few or no cavities were better at breaking down arginine than people with cavities.

They knew bacteria were responsible for breaking down these compounds but needed to study which bacteria do this best, and how this inhibits cavities.
"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?" asked Burne.

"You would implant this probiotic in a healthy child or adult who might be at risk for developing cavities," Burne said.
A12 has a potent ability to battle a particularly harmful kind of streptococcal bacteria called Streptococcus mutans, which metabolises sugar into lactic acid, contributing to acidic conditions in the mouth that form cavities.
The researchers found that A12 not only helps neutralise acid by metabolising 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.

Researchers collected plaque samples for the study. Dental plaque is a mass of bacteria that grows on the surface of teeth and can contribute to the formation of cavities.
They isolated more than 2,000 bacteria that the researchers then screened to find bacteria that fit the bill.
"We then characterised 54 bacteria that metabolised arginine," said Marcelle Nascimento, from University of Florida.
"Out of these, A12 stood out for having all of the properties we were looking for in a bacteria strain that could prevent cavities in a probiotic application," Nascimento said.
The study was published in the journal Applied and Environmental Microbiology.