GM bacteria may banish tooth decay

February 20, 2002 | Source: New Scientist

A mouthful of genetically modified bacteria could keep tooth decay away for life, by replacing your mouth’s natural cavity-causing bacteria with GM bacteria specially designed to prevent tooth decay.
BCS3-L1 can be brushed or squirted onto the teeth in a formulation its creator says tastes like chicken soup. It dramatically reduced cavities in rats but OraGen, Inc., has not yet received permission from the US Food and Drug Administration to test the therapy in humans.

OraGen researchers set out to find a sister strain to the Streptococcus mutans bacteria that was incapable of secreting lactic acid and that also could kill and completely replace S. mutans. Regular S. mutans eats sugar and secretes lactic acid, eating away at tooth enamel.

In the early 1980s, they hit upon a strain that could annihilate S.
mutans
by secreting a toxin known as mutacin 1140. But this new strain still created lactic acid, so the researchers removed the gene that codes for lactase dehydrogenase. Without that key enzyme, mutacin 1140 doesn’t produce lactic acid, thus eliminating the major cause of dental cavities. They call the strain BCS3-L1.

The strain hasn’t been approved for testing on humans yet. However, three human subjects who volunteered to have BCS3-L1′s parent strain applied to their teeth in the early 1980′s still harbour only it and no S. mutans. The volunteers have not passed the strain to their wives and children, evidence that it cannot be spread by kissing.