简介

Our research work is focused on a bacterium, Streptococcus mutans, which colonizes the human mouth from the time of tooth eruption until death. The persistence of the organism is remarkable and our efforts are directed to learning the biological means by which it chronically infects virtually every person in the developed nations. The infection requires two relatively simple-minded objectives: bind to tooth surfaces and then survive in the mouth. However, the mouth is a fairly inhospitable environment, containing between 400 and 500 competing bacterial species, volumes of saliva that are swallowed, desquamating soft tissue surfaces, and the swallowing of food (and adsorbed bacteria) as a bolus. Irreversible binding of tooth surfaces occurs by the action of extracellular enzymes produced by S. mutans, the glucosyltransferases (GTFs). These enzymes catalyze the conversion of sucrose, supplied in our diets, to long-chain, insoluble glucans that serve as the molecular scaffold for the formation of dental plaque. If not removed, physically from teeth, the growing mesh of glucan, food particles, bacteria, and salivary constituents continues to accumulate and forms a biofilm referred to as dental plaque. As plaque builds up, S. mutans becomes protected from the flushing effects of saliva and swallowing. In its protected niche, S. mutans metabolism of sugar results in the formation of organic acids and the rapid acidification of the surrounding milieu. As pH values plummet, several orders of magnitude in just seconds, S. mutans begins its adaptation to life at low pH values, where surrounding bacteria can not compete. Our work is in understanding the mechanisms of low pH adaptation and how it relates to bacterial virulence in biofilms. PhD | Microbiology | Univ Texas-Austin 1984 MS | Genetics | Penn State University 1979 BS | Biology | Penn State University 1977 BS | Biochemistry | Penn State University 1977