Paper Title
The Study of Keratinase from Bacillus Amyloliquefaciensker103

Abstract
A bacterial strain, isolated from the environments, could grow on the casein media and form a clear halo around itself colony. Subsequently,its16S rDNA sequences were identified. This isolated strain designated as B. amyloliquefaciens Ker103. The B. amyloliquefaciens Ker103 was capable of growing on the feather minimal medium. Therefore, a keratinase gene was cloned with His-tag under Ptac promoter in plasmids pET21a. The resulting plasmid pET21a-ker+ was transformed into Escherichia coli BL21. After an IPTG induction, the keratinase protein was purified. The MW of the keratinase was about 28.8 kDa. Under pH 3.0-10.0 and temperature 20-70℃, the keratinase maintains its activity and stability. At pH 9.0 and 60℃, the keratinase has its highest activity. The addition of surfactants, such as Tween 20 and PEG-3350,increased the enzyme activity. In contrast, the keratinase activity was decreased after addition of EDTA, ETOH or NaCl in the mixtures. The soap and SDS surfactants, as well, decrease the enzyme activity. Keywords - Bacillus amyloliquefaciens, Keratinase, Enzyme stability