FIG. 1.

Colony morphology and extracellular protease production by B. subtilis (natto) strains. (A) Strains grown on GSP agar plates for 24 h at 42°C. Only BEST195 formed mucoid colonies. (B) Protease production on agar plates supplemented with skim milk incubated for 17 h at 37°C. Strain UOT1285 (trpC2 lys1 nprR2 nprE18 aprEΔ3) (47) was a non-protease-secreting control strain.