There are about 500 strains of bacteria that inhabit your mouth, but soon you may be thankful for one more. After two decades of effort, University of Florida microbiologist Jeffrey Hillman has created a genetically engineered bacterium that could make cavities a thing of the past. Streptococcus mutans causes tooth decay by breaking down sugar into lactic acid, which destroys tooth enamel. Hillman modified S. mutans so it cannot make lactic acid and produces extra antibiotics that could wipe out its harmful cousin. "We could squirt the solution on the teeth and eliminate the majority of tooth decay with one application," Hillman says.
Some patients might worry about unleashing a modified microbe so close to home, but Hillman insists he's just helping the evolutionary process. Before humans ate so much refined sugar, S. mutans was likely innocuous. In another hundred thousand years or so, natural selection would have shifted it back to a harmless strain anyway. "All we've done is speed up the process," Hillman says. Clinical trials are scheduled to start this year.