Growth conditions for the expression of fibronectin and collagen binding to Salmonella

Binding of 125I-fibronectin, its 125I-labelled 29-kDa aminoterminal fragment, and 125I-collagen to cells of 13 Salmonella strains grown in broth and agar media at three different temperatures was studied. Of the 13 strains, 7 had only smooth colony morphologies while three strains were pairs of both smooth strains and their corresponding rough variants. The three rough variants showed higher binding to fibronectin, it's 29-kDa fragment and to collagen, than the corresponding smooth forms. However, the percentage of 125I-protein bound was greatly influenced by the growth conditions. In these three pairs of strains, there was a direct correlation between cell-surface hydrophobicity and the binding activity, but this correlation was not observed in the remaining strains. Thus, some of the strains showed high cell-surface hydrophobicity but low binding activity under optimal growth conditions. The highest binding rates of fibronectin and of it's 29-kDA fragment were obtained with bacteria grown on colonisation factor antigen (CFA) agar at 33 degrees C, while the binding to collagen was slightly higher when bacteria were cultured on tryptic soy agar.