[Screening, identification and fermentation optimization of a collagenase-producing strain and purification of the collagenase].

Objective: The purpose of this study was to isolate novel strains from the soil nearby meat processing factories to produce collagenase. After the yield of collagenase from the strain improved, the collagenase was purified and used for hydrolyzing collagen. Methods: The strain was identified based on morphological features, physiological and biochemical characteristics and 16S rRNA gene phylogenetic tree analysis. The yield of collagenase was increased by optimizing the fermentation condition, and the collagenase isolated from the fermentation supernatant of the strain was finally purified with strong anion exchange resins. Results: The collagenase-producing strain was identified as Bacillus cereus. The optimized fermentation conditions of the strain were: 2.0% glucose as optimum carbon source, 1.5% tryptone as optimum nitrogen source, 0.005% of Ca2+ as optimum metal ion. The optimum temperature and pH were 37 ℃ and 7.5, respectively. Under the optimum conditions, the enzyme activity of collagenase was (65.81±2.06) U/mL, 1.5-fold increased than that before the optimization. After purified with strong anion exchange resins, a collagenase with the purity higher than 90%, the molecular weight about 100 kDa, and the specific activity of 7615.0±78.7 U/mg was obtained. Conclusion: The activity of Bacillus cereus collagenase was higher than the reported collagenases. Using this novel collagenase, collagen could be degraded into short biological peptides in a short time. Hence, this collagenase has application prospects in many fields, such as food, medical, health care products and cosmetics.