CHAPTER FOUR PROTEOME COMPARISON OF Pseudomonas aeruginosa PLANKTONIC, SURFACE INFLUENCED PLANKTONIC AND BIOFILM POPULATIONS BASED UPON COMPOSITE TWO-DIMENSIONAL ELECTROPHORESIS GELS

It has long been recognised that bacteria can switch from planktonic unicellular organisms to sessile multicellular communities known as biofilms (Costerton et al., 1987; 1995). The transition to surface-attached (biofilm) growth is known to result in diverse changes in gene expression, which causes the attaching cells to become phenotypically and metabolically distinct from their planktonic counterparts (Costerton et al., 1999; Davey and O’Toole, 2000; Stewart and Costerton, 2001). Pseudomonas aeruginosa, a ubiquitous environmental gramnegative bacterium, is one of the most studied biofilm-forming organisms and has emerged as a model organism in the study of surfaceand biofilm-induced gene expression.