Biochemical characterization of a novel surfactant-stable serine keratinase with no collagenase activity from Brevibacillus parabrevis CGMCC 10798

- A novel keratinase-producing bacterium Brevibacillus parabrevis CGMCC 10798 was screened.
- B. parabrevis keratinase with no collagenase activity was purified and characterized.
- The optimum pH and temperature values for keratinase activity were pH 8.0 and 60 °C.
- The enzyme displayed promising application potential in leather industry.

Dehairing is a high pollution process in leather industry. Conventionally, the lime-sulfide mediated chemical process for dehairing would lead to the discharge of pollutants and corrosion of industrial equipment. Concerning these problems, keratinase has become a promising candidate for dehairing process in recent years. In this study, a keratinase-producing bacterium was isolated from sheepfold soil and identified as Brevibacillus parabrevis CGMCC 10798 based on the biochemical characteristics and molecular identification. The keratinase was purified to electrophoretic homogeneity with 17.19% of recovery, 13.18 folds of purification and an estimated molecular weight of 28 kDa. The enzyme exhibited high keratinase activity and no collagenase activity. Besides, the keratinase showed optimal activity at 60 °C and pH 8.0. The enzyme activity could be significantly increased in the presence of Na+ and Ca2+. And it was inhibited by EDTA, and PMSF, which indicated that the keratinase belongs to serine-metallo protease. The enzyme could remain stable in the presence of surfactants. Especially, 5 mM Tween 40 and Triton 100 could improve the activity by 11% and 30%, respectively. Moreover, B. parabrevis keratinase could completely dehair goat wool within 7 h, which indicated its application potential in leather industry.