Expression of Mutated SapB-N99Y Keratinase in Bacillus subtilis DB430 and Its Attractive Properties for Soaking Hides and Skins in the Leather Processing Industry

The mutated sapB-N99Y from Bacillus pumilus CBS keratinase (SAPB) was cloned and expressed in the protease-deficient B. subtilis DB430 using an Escherichia coli-Bacillus shuttle vector pBSMuL2. The SAPB-N99Y enzyme was purified from the culture supernatant of B. subtilis and biochemically characterized. The purified enzyme showed the same biochemical properties of that expressed in E. coli. Further investigations demonstrated that SAPB-N99Y had the highest catalytic efficiency and the best degree of hydrolysis. The mutant enzyme was also noted to exhibit a number of newly explored properties that are highly valued on the marketplace, namely, the potent soaking ability of hides and skins in the leather processing industry. Interestingly, and at the semi-industrial scale, SAPB-N99Y efficiently removed hair from the hides and skins of cow, goat, and sheep within a short time interval of 4 h, thus, offering a promising opportunity for the attainment of a lime-free soaking process. Overall, the findings indicated that SAPB-N99Y is a promising candidate to use in the leather industry.