된장에서 단백질 분해효소를 분비하는 Bacillus cereus SH-7의 특성에 관한 연구

Characterization of Bacillus cereus SH-7 Excreting Protease from Korean Soybean Paste

To know whether or not there are bacteria producing excretory protease in Korean traditional fermented food, soybean paste (Doen-Jang), it was screened by methods of casein and gelatin hydrolysis, and seemingly different groups of bacteria were obtained. One strain was identified to be Bacillus cereus SH-7 through about fifty physiological, biochemical tests, and automatic identification system, VITEK system and MIDI system. This strain was a sporeforming, Gram(+), motile, and rod-shaped bacterium. The strain grew well at pH 7 and 37°C. Its extracellular protease showed optimal activity at pH 8 and 50°C. When 1%(W/V) casein was added to the medium, its activity was increased about 40% at 24 h. Also, hemolysis activity of Bacillus cereus SH-7 was observed.