FIG. 1.
Detection of proteolytic activity in culture supernatants. Protease activity was analyzed in representative experiments by SDS-PAGE-coupled zymography (with casein as the substrate) (A), by native PAGE-coupled zymography (with gelatin as the substrate) (B), and with the chromogen substrate (Fua-LGPA-ase activity of the Brecon/1 strain) (C). In panels A and B, the samples analyzed were the same. The strain designations and culture times (in hours) are indicated above the gels. Note that both the Php-A and Php-C bands are fainter and expressed later in the K122/1 culture than in the Brecon/1 culture. (C) Symbols: ▴, optical density of the culture at 600 nm (OD600); •, enzyme activity (kobs). For the method used to determine kobs, see Materials and Methods.