The Predatory Probiotic That Improves Oral Health

The species has been known for over 80 years, although its influence on our oral health has been explored for only about a decade.

02/22/2018 09:41 EST | Updated 02/22/2018 09:41 EST

If you've ever been in line at a natural health store, you may have come across a rather odd item known as a probiotic chewing gum. As the name implies, the rubbery treat contains millions of bacteria, which at first glance, may not seem remotely pleasant. Yet, taking a closer look at the type of microbe contained within this product,and several other oral health options coming to market, may help to explain why it may be beneficial.

The name of the bacterium is Streptococcus salivarius. Not surprisingly, the most common place to find this bacterium is the mouth. The species has been known for over 80 years, although its influence on our oral health has been explored for only about a decade. The research has shown that its presence can be in maintaining a balanced oral environment. Unfortunately, that is not always guaranteed.

The bacterium becomes part of our internal ecosystem not long after birth, and stays with us until death. At this point, the species has a relatively good control over the environment. However, as we age, the microbial population inside our mouths turns from a rather small community to an incredibly diverse metropolis in which several hundreds of different types of species may colonize various areas and settle in.

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Most will be harmless as they're only interested in taking part in the microbial community. However some will become troublesome and attack us in the process, leading to inflammation, bad breath, cavities and decay. In these cases, the levels of the salivarius bacteria may not be high enough to prevent troubles.

This led researchers to find out if adding the salivarius bacteria to the mouth as a probiotic might help to reduce some of the symptoms of these attacks. In 2006, they tested their theory using bad breath as a marker for improved oral health. They were delighted to see an improvement in the odour after the treatment.

The work fostered other experimental attempts to determine if the bacterium could help keep the mouth safe from cavities, as well as prevent troubles in other nearby areas such as the sinuses and throat. The efforts were again successful. In all cases, the salivarius managed to deal with the troublesome species with little effort.

But while the results of these experiments revealed an obvious benefit, researchers still wondered how this activity progressed. After all, as anyone who has ever seen plaque will attest, bacteria in the mouth tend to clump together and form rather strong colonies, better known as biofilms. Simply adding the salivarius would not always guarantee that an improvement would be seen. Yet, somehow, the bacteria had an unknown ability that allowed it to bring back a healthy state.

The results reveal this species isn't being defensive.

Now thanks to a group of Belgian researchers, we finally may know salivarius' secret. The team has examined how the bacterium interacts with others species and learned what was happening at the molecular level. The results reveal this species isn't being defensive. Instead, it's a predator.

The research was based on the nature of oral biofilms. They're like a crowded marketplace in which different species share numerous different molecules with one another. One of these traded wares happens to be genetic material, such as DNA.

When a valuable piece of DNA is shared between two bacteria, there's the potential for robbery in which another member of the community swoops in and steals the goods. In order to stop this, several species have enacted a personal defense system. Should a potential burglar be sensed, a variety of damage-causing molecules, known as bacteriocins, are released. If those criminal microbes venture into the environment, they're wounded and usually killed.

The team focused on how the salivarius bacteria controlled the production of these bacteriocins. They hoped to find a difference compared to other bacterial species in the mouth. If the group was correct, the bacteria would produce a higher number of these killer molecules, which would give them a very strong edge.

Just be sure to talk with your dental professionals first to let them know you intend to make friends with this predatory probiotic.

What the team found was a surprise. The salivarius were not producing more bacteriocins. They were producing the chemicals earlier than other species. Instead of waiting to sense the presence of a thief, the salivarius began to produce the killing molecules as soon as the chance to get some DNA arrived. This definitely helped to protect the purchase.

But more than that, by killing any nearby potential thieves, the amount of DNA to take in would also increase. This is known ecologically as predation, and as such, made salivarius a predator. Over time, the predatory behaviour could lead to a change in the population, making it less likely to harm us. In essence, the salivarius were single-handedly helping to improve our oral health, explaining the results of previous experiments.

For the authors, this very interesting twist offers a unique perspective on how a beneficial bacterium helps us by having a dark side. The results also provide an opportunity to explore this bacterium as a possible probiotic for more than the oral cavity. As it poses little threat to human health, there may be more options for its use in the future. Until that happens, probiotic oral products, such as gum, pastilles and tablets, may offer a possible route to health improvement. Just be sure to talk with your dental professionals first to let them know you intend to make friends with this predatory probiotic.