Pseudomonas aeruginosa is a common soil and aquatic bacterial species that forms surface-associated communities called biofilms. Biofilms are considered to be the predominant bacterial lifestyle in the environment and P. aeruginosa is the paradigm species for their study in the laboratory. Biofilm bacteria produce one or more extracellular polymeric substances (EPS) that act as a scaffold, holding biofilm cells together and to a surface. Key EPS components include exopolysaccharides, nucleic acids and proteins. Despite P. aeruginosa being the paradigm species for biofilm study, very little is known regarding the composition and regulation of this matrix. For some time, alginate has been considered the major exopolysaccharide of the P. aeruginosa EPS matrix. Recent work from the PI's laboratory indicates that alginate is not a significant component of the EPS matrix of P. aeruginosa environmental isolates. Instead, there appear to be other polysaccharide components that are important for biofilm formation. Previous work discovered that P. aeruginosa has the capacity to encode two alternative, secreted polysaccharides, designated Psl and Pel, which play critical roles in cell surface interactions and biofilm formation. The focus of this project is the Pel polysaccharide. Very little is known regarding Pel's regulation, structure and contribution to biofilm formation. The overall objectives are to identify the genetic determinants that encode Pel production; to gain insight into the structure of Pel; and to examine the regulation of Pel and its contribution to biofilm structure and function. Since findings regarding P. aeruginosa biofilms have been shown to be broadly applicable to other environmental biofilm forming species, it is expected that this project will provide new insight into how bacteria hold together in environmental biofilms.
Broader Impact The project will have broader, educational impact in several ways. In particular the project will provide research experiences for high school students, outreach activities in K-12 schools, and curriculum development activities at the University of Washington. A high school student from the local area as well as a student recruited through the AgriScience Research Program at Uniondale Public School will conduct research during the summer with the PI. The AgriScience Research Program is an established program for gifted students at Uniondale Public Schools which is located on the outskirts of New York City and has a highly diverse student body. The project will provide an opportunity for the selected high school students to initiate an independent summer research project. Specifically the students will isolate P. aeruginosa from environmental samples and determine the presence/absence of the Pel gene cluster. For outreach to K-12 schools the PI will make presentations at the local elementary schools, highlighting microbial communities (with an emphasis on biofilms). The goal of the presentations is to introduce elementary school students to bacteria and the role of bacteria in the ecosystem. To support curriculum development at the University of Washington, the PI will develop a Systems Ecology Module as a component of a graduate level class in Microbial Ecology. The module will focus on the tools of systems biology and applications of the tools to complex systems, using laboratory biofilms as model complex systems. The module will encourage future scientists to apply the tools that are emerging from genomics efforts to complex systems and promote advancements in molecular microbial ecology.
