Comparison of protein expression profiles of planktonic and mature S. pneumoniae biofilms. A) Crude protein extracts (50 μg) of S. pneumoniae grown under planktonic (PK) or biofilm (BF) conditions separated by SDS-PAGE using 12% polyacrylamide gels and silver stained. B) Representative 2DGE images of total cell lysates of S. pneumoniae TIGR4 grown planktonically and as a 2 day old biofilm. Crude protein extracts (300 μg) were separated on pH 3.0-5.6 Immobiline Dry strips followed by SDS-PAGE using 8-16% polyacrylamide gels. Gels were stained with Coomassie blue.