New application of SptA protease: A cleaner and potential water-conserving approach to dehairing of skin

Abstract

Leather making technology is undergoing a profound change from chemical process to enzyme-assisted dehairing. In this work, the SptA protease from halophilic archaeon Natrinema sp. J7 was expressed by Bacillus subtilis SCK6. The crude enzyme extract was applied into enzymatic dehairing process with the enzyme activity of 1800 U/mL. Histologic analysis, scanning electron microscope and wastewater test indicated this SptA protease could serve as a good alternative to sodium sulphide in goatskins dehairing technique. Noteworthily, 8% sodium chloride was introduced in SptA protease dehairing system and achieved a comparable result after 6 h of treatment. This would not only reduce the pollution load significantly, but also bring about 16–20% water-conserving benefit by addressing the issue of high salt in the preservation of hides and skins. In addition, based on bioinformatics, molecular modelling and docking analysis were made as an attempt to illustrate how SptA protease contribute to the loosing and removal of hair from the micro and molecule perspective. It was concluded that this SptA protease could efficiently dehair goatskins without any damage to the grain and collagen structure, ensuring its use as a promising candidate for leather making.