FIG. 3.

Analysis of extracellular proteins produced by S. liquefaciens MG1 and different mutant strains. Cultures were grown in LB medium in the presence or absence of 200 nM C4-HSL for 16 h as indicated. The protein molecular mass standard (lanes S) consists of proteins of 196, 118, 90, 70, 55, 38, and 33 kDa. Enzymatic activities of sterile filtered supernatants were visualized with the aid of zymograms as described in the text. The SlaA protein was visualized by immunoblotting with antisera against SlaA. wt, wild type.