Skin unhairing proteases of Bacillus subtilis: production andpartial characterization

Proteases able to unhair sheep skins were produced from Bacillus subtilis. Protease activity was increased from 640 to 990 U/mL by using a fed-batch culture with glucose added sequentially up to 10 g/L. The crude enzyme prep-aration was mainly a mixture of metallo- and serine-proteases with optimal pH and temperature for protease activity at 7 and 50-55°C, respectively. At pH 8 and 30°C, protease activity of the crude enzyme was 33% of the maximal value and 97% of the original activity (900 U/mL) was retained after incubation for 4 hours.