[Screening of collagenase-producing strain and purification of Bacillus cereus collagenase].

We isolated the strain MBL13 with high collagenase productivity from the soil of piled up animal bones. It was identified as Bacillus cereus. We purified and characterized Bacillus cereus collagenase (BCC). The molecular weight of BCC was 38.0 kDa and the optimum temperature and pH for the enzyme activity were 40 degrees C and 8.0 respectively. The enzyme was stable when the temperature was below 50 degrees C, but only retained 10% activity when kept at 60 degrees C for 1 h. The enzyme activity was stable between pH 7.0-8.5. Some metal ions such as Ca2+, Zn2+, Mg2+ enhanced the enzyme activity, and Cu2+ brought the obvious inhibition. In addition, EDTA and EGTA could inhibit the enzyme activity. We suggested that the purified enzyme was a member of the metalloproteases. Based on the experiment of substrate specificity, we found that the purified enzyme was bone collagenolytic protease, and had a much stronger capacity of hydrolysis for type I collagen than that for type II collagen and type III collagen. By BCC hydrolyzing bone collagen, we obtained polypeptides with different chain lengths. The comparative test indicated that the hydrolysis capacity of BBC was higher than that of standard type I collagenase. The results introduced a new strain and a novel collagenolytic protease for industrial enzyme.