Project Summary Biofilm formation has been linked to many chronic bacterial infections. Thus, significant research has been directed towards understanding the basic biology behind biofilm formation. Biofilms produce an extracellular matrix that functions, in part, to hold the community together. Pseudomonas aeruginosa represents a paradigm species for the study of biofilms in the laboratory. The regulation of matrix production and the carbohydrate component of the matrix have both been examined. However, the protein component of the biofilm matrix has been relatively understudied. Our groups identified a biofilm matrix protein for P. aeruginosa, CdrA. CdrA provides structural integrity through extracellular interactions with the matrix polysaccharide Psl. Outside of matrix proteins that provide structural functions, we predict that matrix associated proteins can play both nutritional and protective roles for the community. This project will initially focus on CdrA and its role in the matrix. We will then characterize ecotin a matrix bound protease inhibitor and three matrix-associated proteases. Finally, we will identify new matrix proteins that associate with eps component of the biofilm matrix.