Fig. 2
Effects of different single promoters on the overexpression of NK. (a) Fibrinolytic activities of NK in the supernatant. The recombinant strains having different single promotes were cultured in TB medium for 72 h with periodical sampling. b SDS-PAGE analysis. Recombinant strains having different single promoters were cultured in the TB medium for 36 h, and then the cells and the supernatant culture were separated by centrifugation. Supernatant (15 μL) was loaded into each lane. Lane M: standard marker proteins; Lane 1–6: PHpaII; PP43; PBcaprE; PluxS; PgsiB and PyxiE. The arrow indicates that the NK bands correspond to 36-h supernatant. c Fibrin plate analysis. Transparent zones produced by the enzyme activity of NK and its variants in the supernatant, which was induced for 36 h, were examined by the fibrin plate method, which was conducted at 37 °C for 4 h. 1–6: PHpaII; PP43; PBcaprE; PluxS; PgsiB and PyxiE