High-expression keratinase by Bacillus subtilis SCK6 for enzymatic dehairing of goatskins.

An extracellular keratinase gene from Bacillus sp. LCB12, isolated from saline-alkali soil, was cloned and high-effectively expressed in Bacillus subtilis SCK6. The enzyme was purified by ammonium sulphate precipitation and cation-exchange chromatography. Its molecular mass was estimated to be 30.95 kDa by SDS-PAGE. The optimum conditions for catalytic activity of the enzyme were pH 10.0 and 60 °C. The enzyme activity was completely inhibited by PMSF, while it was slightly inhibited by EDTA. Moreover, the surfactants Tween 20, Tween 80 and Triton X-100, showed little effect on enzyme activity respectively. The crude enzyme was used as an alternative to sodium sulfide for dehairing of goat skins. The goatskin was dehaired by the enzyme at 33-35 °C in 6 h. The enzymatic dehaired pelt showed better general appearance and better whiteness by visual tests, and the grain surface of enzymatic dehaired pelt revealed absence of hair shaft with empty follicles by stereoscopic observation. Meanwhile, the epidermis was completely removed and the collagen fiber structure of enzymatic dehaired pelt was more opened, regular and even in dermis comparing with conventional dehaired pelt by histological analysis.