An ammonium sulfate precipitation of
fermentation broth produced by Bacillus subtilis FBL-1
resulted in 2.9-fold increase of specific protease activity.
An eluted protein fraction from the column chromatographies
using DEAE-Cellulose and Sephadex G-75 had 94.2- and
94.9-fold higher specific protease activity, respectively.
An SDS-PAGE revealed a band of purified protease at
approximately 37.6 kDa. Although purified protease showed
the highest activity at 45°C and pH 9.0, the activity remained stable in temperature range from 30 to 50°C and pH range from 7.0 to 9.0. Protease activity was activated by metal ions such as Ca2+, Mg2+, Mn2+, Fe2+, Ca2+ and K+, but
10 mM Fe3+ significantly inhibited enzyme activity (53%).
Protease activity was inhibited by 2 mM EDTA as a
metalloprotease inhibitor, but it showed good stability
against surfactants and organic solvents. The preferred
substrates for protease activity were found to be casein
(100%) and soybean flour (71.6%)
