Grant: Operating Grant

Streptococcus mutans is a bacterium that lives in dental plaque and is known to cause cavities. It is able to dissolve the tooth enamel by converting dietary sugars into acids. By producing acids it also lowers the pH of the plaque environment causing a shift in the populations of the many normal bacteria that live in 'healthy' plaque. S. mutans has evolved specialized mechanisms that allow it to withstand an acidic environment, giving it an 'ecological edge' over these other bacteria. One of the main features of S. mutans is its acid tolerance that gives it the ability to survive in acid that it and other bacteria produce from sugars. The aim of this project is to gain understanding of the genes and enzymes that the bacterium uses so that we may eventually block this process, hopefully stopping the ecological changes in dental plaque that lead to cavities. We have already identified a number of proteins involved in the process and now wish to examine the genes involved. We have used DNA microarrays to help us determine which genes are activated when S. mutans senses a pH drop. We are now examining the proteins that S. mutans uses to sense its environment hopefully to find the switches that turn on the genes. We are also examining a way of blocking protective metabolic activities that S. mutans uses to survive low pH. Ultimately our goal is to design a treatment that will prevent healthy plaque from becoming 'caries-causing' plaque.