Research in the Duncan lab focuses on how bacteria respond to environmental signals and become disease causing (‘pathogenic’). Humans live peacefully with billions of microorganisms on and in their bodies. In reality, this benign coexistence is based on a dynamic and delicate equilibrium, the result of millions of years of co-evolution. Tip the balance, and organisms that are normally harmless can become pathogenic. Such a balancing act goes on among the many bacterial species living in the mouth. A change in the environment can upset this harmony, triggering gum disease (periodontitis) or tooth decay. A major interest of the Duncan group is gene regulation in Porphyromonas gingivalis, the organism most often associated with periodontal disease, and in Streptococcus mutans, the major causative agent of dental caries.
“I am interested in deciphering the “conversation” between bacteria and the body,” said Duncan. “This interaction during infection is central to understanding microbial pathogenesis and host defense.” In bacteria many of these interactions are regulated by so-called two-component signal transduction systems that respond to environmental cues from the human host. A long-term goal of the Duncan laboratory is to identify genes in both P. gingivalis and S. mutans that are regulated by these systems and expressed during infection, i.e. one side of the cross-talk between bacterium and host.