Pseudomonas Global Regulatory Networks in Biofilms

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Our view of bacteria growing in any environment is changing as we gain more information on how bacteria grow as microbial communities, called biofilms. Perhaps the most interesting aspect of microbial communities is that the bacteria can communicate and coordinate their responses such that they operate in a manner similar to simple multicellular organisms. Bacteria control these community behaviours using systems called global regulatory networks. These systems allow the bacterial population to sense, respond, communicate and coordinate their responses. We are interested in three global regulatory systems: the stringent response which allows cells to sense and respond to nutrient limitation; quorum sensing which allows bacteria to sense their neighbours, respond and coordinate the population; and the GacA/S two component system involved in biofilm formation and maintenance. The goal of this research is to understand how these three systems work together in a bacterial biofilm. To carry out this research we will use a bacterium called Pseudomonas aeruginosa, known for its ability to form biofilms and its role in biofilm infections. We will examine the genes induced and repressed by these systems and in particular look for genes that overlap in at least two of these systems. We will use mutants in the global regulatory systems to examine their effect on the other systems. For instance we will use mutants in the stringent response to examine their effects on quorum sensing and the GacA/S system. Finally, we will examine the role of each of the global regulatory systems in the antibiotic resistance and their overall role in bacterial stress responses. This research will give us a better understanding of how bacteria form bacterial communities and potentially lead to the development of targets for new antibacterial therapies.