Characterization of processing and activation of Mpr in different B. subtilis strains. SDS-PAGE analysis (A), Western blotting (B), and artificial substrate colorimetric assay (C) of the culture supernatants of different B. subtilis strains carrying pMprH6. Lanes 1, B. subtilis 168; lanes 2, DB104; lanes 3, SB300; lanes 4, PB300; lanes 5, DB428; lanes 6, LB700. p, precursor; m, mature; Abs410nm, absorbance at 410 nm.