Streptococcus mutans or S. mutans, the dominant bacterium in our mouths, latches onto teeth, eats sugar, and then secretes acid, making the bacteria the number-one cause of tooth decay around the world. The secret of its success? The bacterium rearranges its cell membranes to make itself impervious to the acid assault that it lets loose.
"Right now there are millions of bacteria in your mouth, eating sugars and excreting acid which is eating your teeth," says Robert Quivey Jr., Ph.D., a microbiologist and an associate professor in the Center for Oral Biology. "That's why proper oral hygiene, such as brushing, flossing and regular dental check-ups, are so important, to rid the mouth of these bacteria."
In a paper in the July 1 issue of the Journal of Bacteriology, Quivey and graduate student Elizabeth Fozo discuss a vulnerability of S. mutans, a bug that infects almost everyone. Scientists have known for some time that the microbe specially modifies itself once it starts producing acid in the mouth. The Quivey group has shown that the changes include shuffling fatty acids in its membrane much like a bricklayer might move bricks to fortify a fence so it can withstand the wash of acids that it sends pouring into the mouth.
The Rochester team found that a gene known as fabM is responsible for changing the membrane's composition and enables S. mutans to become more resistant to acid. The same gene had previously been discovered in a similar bug that causes a type of virulent pneumonia, in research by a group led by Charles Rock at St. Jude Children's Research Hospital in Memphis