Bacterium Altered to Fight Tooth Decay

A bacterium called Lactobacillus zeae, found in many dairy products like yogurt, has been genetically altered to aid in the fight against dental caries (cavities). The mutans group of streptococci causes most dental caries (cavities). This group of bacteria contains several different streptococcal species. Streptococcus mutans and Streptococcus sobrinus are the ones commonly found in humans. They use surface attachment molecules (adhesins) to bind to the surface of teeth. In time if not removed from the tooth surface the bacteria multiply and make acids that destroy the surface of the tooth causing a cavity.

The July 2002 issue of Nature Biotechnology contains the data of a study in which a bacterium Lactobacillus zeae was given genes that causes it to produce an antibody on its surface. The antibody attaches to the adhesin on the surface of Streptococcus mutans. The two different bacteria, Lactobacillus zeae with its surface antibody and Streptococcus mutans cells, clump together and slide harmlessly down the throat.

A group of European scientists led by Swedish researcher Lennart Hammarström set out to see whether Lactobacillus could be genetically altered to both produce an antibody that prevented Streptococcus mutans from binding to the tooth surfaces and would be effective over long periods of time. When they gave the genetically altered Lactobacillus to rats that had been infected with the cavity-causing pathogen Streptococcus mutans, they found that the Lactobacillus reduced not only the number of streptococcal bacteria, but also the number of cavities they produced. In contrast to antibody given by itself, which is quickly broken down and/or was removed from the mouth, the Lactobacillus bacteria were able to live in the rat's mouths for three weeks, continually fighting the bacteria that cause cavities.

Who knows if this work continues on maybe someday our children will be telling their children that a yogurt a day keeps the dentist's drill away.

For more information go to the following websites:

http://www.nature.com/nbt/press_release/nbt0702.html
http://www.nature.com/nbt/
http://www.nature.com/nsu/020624/020624-9.html

Take Care and Think Microbiologically! For more microbiology articles go to Suite101:Microbiology.

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