Sunday, July 3, 2011

Natural-Occurring Cavity Fighters: Streptococcus Salivarius


The mouth has over 700 different species of bacteria living in it, some of which are harmful and others that are actually beneficial for the host. Plaque, the cause of cavities, is made by the formation of biofilms. Those bacteria that produce the biofilms causing plaque are called Streptococcus Mutans. S. mutans digests sugars and produces acids that can eat into enamel and cause cavities (Science Magazine). Streptococcus salivarius are other bacteria commonly found in the oral cavity, however, these bacteria are beneficial. These bacteria quickly take up residence in the mouth after a day of life or so and they mostly live on the tongue. Streptococcus salivarius is a spherical, gram-positive bacteria. The S. salivarius bacteria is an opportunistic pathogen, which means it is harmless to those with a healthy immune system, but when the immune system becomes compromised it can become harmful. Just recently in 2009, these bacteria were discovered to help play a part in prevention of plaque formation by secreting an enzyme that breaks down the buildup of Streptococcus mutan bioflim.

Hidenobu Senpuku, a scientist in Tokyo, wanted to see which enzyme in S. salivarius breaks down plaque. Using chromatography, he separated out the different proteins from the bacteria. He found that the enzyme, FruA, inhibited the growth of S. mutans cells the most. This is probably because this enzyme is used in the S. salivarius bacteria to break down complex sugars.

Researchers then found that another form of the enzyme, FruA, is also produced by a fungus. Aspergillus niger is a common fungus that produces FruA, but has a slightly different amino acid sequence than the S. salvarius FruA, but it still contains plaque fighting abilities. The discovery of FruA in the Aspergillus niger fungus could make the possibility of toothpaste containing the enzyme, FruA, available in the near future. It would still be very difficult to create a toothpaste with a perfect balance that would allow the enzyme to stay in tack and be able to function once used.

So does the fact that humans produce natural plaque reducers mean that we can stop brushing our teeth as often? Unfortunately, no it doesn’t. Researchers found that the enzyme will stop working if overloaded with sugars. It won’t be able to fight of the formation of biofilms which can cause cavities.

The more scientists find out about the S. Salivarius bacterium, the better. “A better knowledge of the molecular and physiologic factors which allow it to colonize dental plaque and to interact with other species will help in designing strategies for the prevention of cavities, especially in children (Genoscope).”

Resources:

http://news.sciencemag.org/sciencenow/2011/04/a-bacterium-that-acts-like-a-toothbrush.html

http://www.genoscope.cns.fr/spip/Streptococcus-salivarius,483.html

http://aem.asm.org/cgi/content/full/77/5/1572

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