Bacteria to Prevent Cavities?

A study published in “Applied and Environmental Microbiology” in January 2016: “Characterization of a highly arginolytic Streptococcus species that potently antagonizes Streptococcus mutans”, outlines how a novel Streptococcus, designated A12, is able to inhibit the growth of Streptococcus mutans, the bacteria responsible for causing tooth decaying cavities.

Streptococcus mutans

A photomicrograph of Streptococcus mutans bacteria using Gram stain technique.
Blood agar plate culture yields coccal-like morphology without chains. The S. mutans organism can cause subacute bacterial endocarditis and dental caries. Courtesy: CDC/ Dr. Richard Facklam

The metabolism by S.mutans of sucrose (the sugar found in food) into lactic acid demineralizes teeth thereby leading to decay. Sucrose is also used by S. mutans to product a sticky polysaccharide that allows the bacteria to create a biofilm that helps S.mutans stick to tooth surfaces. A “biofilm forms when bacteria adhere to surfaces in moist environments by excreting a slimy, glue-like substance.” The plaque on teeth is a biofilm.

The new Streptococcus A12 strain found by Robert Burne, Ph.D., associate dean for research and chair of the UF College of Dentistry’s department of oral biology, and Marcelle Nascimento, D.D.S., Ph.D., an associate professor in the UF College of Dentistry’s department of restorative dental sciences, fights tooth decay four ways:

  1. Metabolizes arginine in the mouth into ammonia and urea (raises pH) thereby neutralizing the acidic effect of lactic acid
  2. Interferes with the growth of S.mutans by producing hydrogen peroxide
  3. Interferes with the growth of S.mutans by producing a protease similar to Challisin (Sgc) of Streptococcus gordonii that was able to block the CSP-ComDE signaling system, which is essential for bacteriocin (antimicrobial peptides or proteins produced by bacteria) production by S. mutans
  4. Reduces S.mutans’ ability to form biofilms

What remains to be done is to understand how the A12 strain might be applied or dosed to prevent tooth decay.

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